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.
13220 vulnerabilities reference this CWE, most recent first.
GHSA-69XR-M8H6-H664
Vulnerability from github – Published: 2026-05-06 23:42 – Updated: 2026-05-14 20:43Description
A vulnerability exists in the X-Forwarded-Prefix header processing logic within Angular SSR. The internal validation mechanism fails to properly account for URL-encoded characters, specifically dots (%2e%2e). This allows an attacker to bypass security filters by injecting encoded path traversal sequences that are later decoded and utilized by the application logic.
When an Angular SSR application is configured to trust proxy headers and is deployed behind a proxy that forwards the X-Forwarded-Prefix header without prior sanitization, an attacker can provide a payload such as /%2e%2e/evil.
The vulnerability manifests in two ways:
- Open Redirect: The application processes a redirect (e.g., router redirectTo). The decoded traversal payload manipulates the Location header, forcing the browser to an unintended path or external domain.
- Server-Side Request Steering: The manipulated prefix is used as the base path for server-side HttpClient requests. This causes the server to make requests to unintended internal paths or external endpoints.
Attack Preconditions
- The application must use Angular SSR.
- The application must perform internal redirects or use relative URLs in server-side
HttpClientrequests. - The upstream infrastructure (Reverse Proxy/CDN) must pass the
X-Forwarded-Prefixheader to the SSR process without stripping or sanitizing it.
Workarounds
Until the patch is applied, developers should manually sanitize the X-Forwarded-Prefix header in their server.ts. The workaround involves decoding the component to catch encoded traversal attempts before normalization:
app.use((req, res, next) => {
let prefix = req.headers['x-forwarded-prefix'];
if (Array.isArray(prefix)) prefix = prefix[0];
if (prefix) {
try {
// Decode the prefix to catch encoded characters like %2e (dots)
const decodedPrefix = decodeURIComponent(prefix);
// Sanitize: remove traversal attempts and ensure a safe leading slash
req.headers['x-forwarded-prefix'] = decodedPrefix
.replace(/\.\./g, '') // Remove any dot-dot sequences
.replace(/^[/\\]+/, '/'); // Ensure it starts with exactly one slash
} catch (e) {
// If decoding fails, remove the potentially malicious header entirely
delete req.headers['x-forwarded-prefix'];
}
}
next();
});
Configuring Trusted Proxy Headers
By default, Angular ignores all X-Forwarded-* headers. If your application is behind a trusted reverse proxy (like a load balancer) that sets these headers, you can configure Angular to trust them. You can configure trustProxyHeaders when initializing the application engine:
const appEngine = new AngularAppEngine({
// Trust specific headers
trustProxyHeaders: ['x-forwarded-host', 'x-forwarded-proto', 'x-forwarded-prefix'],
});
const nodeAppEngine = new AngularNodeAppEngine({
// Trust all X-Forwarded-* headers
trustProxyHeaders: true,
});
Patches
- 22.0.0-next.7
- 21.2.9
- 20.3.25
- 19.2.25
Resources
- https://github.com/angular/angular-cli/pull/33031
- https://angular.dev/best-practices/security#configuring-trusted-proxy-headers
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "@angular/ssr"
},
"ranges": [
{
"events": [
{
"introduced": "22.0.0-next.0"
},
{
"fixed": "22.0.0-next.7"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "npm",
"name": "@angular/ssr"
},
"ranges": [
{
"events": [
{
"introduced": "21.0.0-next.0"
},
{
"fixed": "21.2.9"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "npm",
"name": "@angular/ssr"
},
"ranges": [
{
"events": [
{
"introduced": "20.0.0-next.0"
},
{
"fixed": "20.3.25"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "npm",
"name": "@angular/ssr"
},
"ranges": [
{
"events": [
{
"introduced": "19.0.0-next.0"
},
{
"fixed": "19.2.25"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-44437"
],
"database_specific": {
"cwe_ids": [
"CWE-22",
"CWE-601"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-06T23:42:10Z",
"nvd_published_at": "2026-05-13T22:16:44Z",
"severity": "MODERATE"
},
"details": "### Description\nA vulnerability exists in the `X-Forwarded-Prefix` header processing logic within Angular SSR. The internal validation mechanism fails to properly account for URL-encoded characters, specifically dots (`%2e%2e`). This allows an attacker to bypass security filters by injecting encoded path traversal sequences that are later decoded and utilized by the application logic.\nWhen an Angular SSR application is configured to trust proxy headers and is deployed behind a proxy that forwards the `X-Forwarded-Prefix` header without prior sanitization, an attacker can provide a payload such as `/%2e%2e/evil`.\n\nThe vulnerability manifests in two ways:\n- Open Redirect: The application processes a redirect (e.g., router `redirectTo`). The decoded traversal payload manipulates the Location header, forcing the browser to an unintended path or external domain.\n- Server-Side Request Steering: The manipulated prefix is used as the base path for server-side `HttpClient` requests. This causes the server to make requests to unintended internal paths or external endpoints.\n\n### Attack Preconditions\n- The application must use Angular SSR.\n- The application must perform internal redirects or use relative URLs in server-side `HttpClient` requests.\n- The upstream infrastructure (Reverse Proxy/CDN) must pass the `X-Forwarded-Prefix` header to the SSR process without stripping or sanitizing it.\n\n### Workarounds\nUntil the patch is applied, developers should manually sanitize the `X-Forwarded-Prefix` header in their `server.ts`. The workaround involves decoding the component to catch encoded traversal attempts before normalization:\n\n\n```ts\napp.use((req, res, next) =\u003e {\n let prefix = req.headers[\u0027x-forwarded-prefix\u0027];\n if (Array.isArray(prefix)) prefix = prefix[0];\n\n if (prefix) {\n try {\n // Decode the prefix to catch encoded characters like %2e (dots)\n const decodedPrefix = decodeURIComponent(prefix);\n \n // Sanitize: remove traversal attempts and ensure a safe leading slash\n req.headers[\u0027x-forwarded-prefix\u0027] = decodedPrefix\n .replace(/\\.\\./g, \u0027\u0027) // Remove any dot-dot sequences\n .replace(/^[/\\\\]+/, \u0027/\u0027); // Ensure it starts with exactly one slash\n } catch (e) {\n // If decoding fails, remove the potentially malicious header entirely\n delete req.headers[\u0027x-forwarded-prefix\u0027];\n }\n }\n next();\n});\n```\n### Configuring Trusted Proxy Headers\nBy default, Angular ignores all X-Forwarded-* headers. If your application is behind a trusted reverse proxy (like a load balancer) that sets these headers, you can configure Angular to trust them.\nYou can configure trustProxyHeaders when initializing the application engine:\n\n```ts\nconst appEngine = new AngularAppEngine({\n // Trust specific headers\n trustProxyHeaders: [\u0027x-forwarded-host\u0027, \u0027x-forwarded-proto\u0027, \u0027x-forwarded-prefix\u0027], \n});\n\nconst nodeAppEngine = new AngularNodeAppEngine({\n // Trust all X-Forwarded-* headers\n trustProxyHeaders: true, \n});\n```\n\n### Patches\n- 22.0.0-next.7\n- 21.2.9\n- 20.3.25\n- 19.2.25\n\n### Resources\n\n- https://github.com/angular/angular-cli/pull/33031\n- https://angular.dev/best-practices/security#configuring-trusted-proxy-headers",
"id": "GHSA-69xr-m8h6-h664",
"modified": "2026-05-14T20:43:37Z",
"published": "2026-05-06T23:42:10Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/angular/angular-cli/security/advisories/GHSA-69xr-m8h6-h664"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44437"
},
{
"type": "WEB",
"url": "https://github.com/angular/angular-cli/pull/33031"
},
{
"type": "WEB",
"url": "https://angular.dev/best-practices/security#configuring-trusted-proxy-headers"
},
{
"type": "PACKAGE",
"url": "https://github.com/angular/angular-cli"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Angular SSR has Open Redirect and Request Steering via Encoded X-Forwarded-Prefix"
}
GHSA-6C3W-CF6G-QMGH
Vulnerability from github – Published: 2026-03-31 18:31 – Updated: 2026-03-31 18:31A vulnerability was found in CMS Made Simple up to 2.2.22. This impacts the function _copyFilesToFolder in the library modules/UserGuide/lib/class.UserGuideImporterExporter.php of the component UserGuide Module XML Import. The manipulation results in path traversal. It is possible to launch the attack remotely. The exploit has been made public and could be used. This issue has been reported early to the project. They confirmed, that "this has already been discovered and fixed for the next release."
{
"affected": [],
"aliases": [
"CVE-2026-5203"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-03-31T16:16:35Z",
"severity": "MODERATE"
},
"details": "A vulnerability was found in CMS Made Simple up to 2.2.22. This impacts the function _copyFilesToFolder in the library modules/UserGuide/lib/class.UserGuideImporterExporter.php of the component UserGuide Module XML Import. The manipulation results in path traversal. It is possible to launch the attack remotely. The exploit has been made public and could be used. This issue has been reported early to the project. They confirmed, that \"this has already been discovered and fixed for the next release.\"",
"id": "GHSA-6c3w-cf6g-qmgh",
"modified": "2026-03-31T18:31:31Z",
"published": "2026-03-31T18:31:31Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-5203"
},
{
"type": "WEB",
"url": "https://drive.proton.me/urls/Q0JHZ339BW#X9P2G3Guwvwa"
},
{
"type": "WEB",
"url": "https://vuldb.com/submit/772855"
},
{
"type": "WEB",
"url": "https://vuldb.com/vuln/354331"
},
{
"type": "WEB",
"url": "https://vuldb.com/vuln/354331/cti"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:L",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-6C3X-XHX8-9WX5
Vulnerability from github – Published: 2022-05-13 01:42 – Updated: 2022-05-13 01:42On Cisco DDR2200 ADSL2+ Residential Gateway DDR2200B-NA-AnnexA-FCC-V00.00.03.45.4E and DDR2201v1 ADSL2+ Residential Gateway DDR2201v1-NA-AnnexA-FCC-V00.00.03.28.3 devices, there is no access control for info.html, wancfg.cmd, rtroutecfg.cmd, arpview.cmd, cpuview.cmd, memoryview.cmd, statswan.cmd, statsatm.cmd, scsrvcntr.cmd, scacccntr.cmd, logview.cmd, voicesipview.cmd, usbview.cmd, wlmacflt.cmd, wlwds.cmd, wlstationlist.cmd, HPNAShow.cmd, HPNAView.cmd, qoscls.cmd, qosqueue.cmd, portmap.cmd, scmacflt.cmd, scinflt.cmd, scoutflt.cmd, certlocal.cmd, or certca.cmd.
{
"affected": [],
"aliases": [
"CVE-2017-11589"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2017-07-24T00:29:00Z",
"severity": "CRITICAL"
},
"details": "On Cisco DDR2200 ADSL2+ Residential Gateway DDR2200B-NA-AnnexA-FCC-V00.00.03.45.4E and DDR2201v1 ADSL2+ Residential Gateway DDR2201v1-NA-AnnexA-FCC-V00.00.03.28.3 devices, there is no access control for info.html, wancfg.cmd, rtroutecfg.cmd, arpview.cmd, cpuview.cmd, memoryview.cmd, statswan.cmd, statsatm.cmd, scsrvcntr.cmd, scacccntr.cmd, logview.cmd, voicesipview.cmd, usbview.cmd, wlmacflt.cmd, wlwds.cmd, wlstationlist.cmd, HPNAShow.cmd, HPNAView.cmd, qoscls.cmd, qosqueue.cmd, portmap.cmd, scmacflt.cmd, scinflt.cmd, scoutflt.cmd, certlocal.cmd, or certca.cmd.",
"id": "GHSA-6c3x-xhx8-9wx5",
"modified": "2022-05-13T01:42:26Z",
"published": "2022-05-13T01:42:26Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2017-11589"
},
{
"type": "WEB",
"url": "http://seclists.org/fulldisclosure/2017/Jul/26"
}
],
"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:H",
"type": "CVSS_V3"
}
]
}
GHSA-6C45-7V56-5RVC
Vulnerability from github – Published: 2022-05-17 00:46 – Updated: 2022-05-17 00:46Directory traversal vulnerability in download.php in BuzzyWall 1.3.1 allows remote attackers to read arbitrary local files via a .. (dot dot) in the id parameter.
{
"affected": [],
"aliases": [
"CVE-2008-4759"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2008-10-28T02:00:00Z",
"severity": "MODERATE"
},
"details": "Directory traversal vulnerability in download.php in BuzzyWall 1.3.1 allows remote attackers to read arbitrary local files via a .. (dot dot) in the id parameter.",
"id": "GHSA-6c45-7v56-5rvc",
"modified": "2022-05-17T00:46:36Z",
"published": "2022-05-17T00:46:36Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2008-4759"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/46123"
},
{
"type": "WEB",
"url": "https://www.exploit-db.com/exploits/6835"
},
{
"type": "WEB",
"url": "http://securityreason.com/securityalert/4520"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/31914"
},
{
"type": "WEB",
"url": "http://www.vupen.com/english/advisories/2008/2925"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-6C5F-M57X-3368
Vulnerability from github – Published: 2026-04-03 18:31 – Updated: 2026-04-03 18:31The Stackfield Desktop App before 1.10.2 for macOS and Windows contains a path traversal vulnerability in certain decryption functionality when processing the filePath property. A malicious export can write arbitrary content to any path on the victim's filesystem.
{
"affected": [],
"aliases": [
"CVE-2026-28373"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-04-03T17:16:42Z",
"severity": "CRITICAL"
},
"details": "The Stackfield Desktop App before 1.10.2 for macOS and Windows contains a path traversal vulnerability in certain decryption functionality when processing the filePath property. A malicious export can write arbitrary content to any path on the victim\u0027s filesystem.",
"id": "GHSA-6c5f-m57x-3368",
"modified": "2026-04-03T18:31:23Z",
"published": "2026-04-03T18:31:23Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-28373"
},
{
"type": "WEB",
"url": "https://www.rcesecurity.com/2026/03/stackfield-desktop-app-rce-via-path-traversal-and-arbitrary-file-write-cve-2026-28373"
},
{
"type": "WEB",
"url": "https://www.rcesecurity.com/advisories/cve-2026-28373"
},
{
"type": "WEB",
"url": "https://www.stackfield.com/desktop-apps"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-6C69-W7WC-QM57
Vulnerability from github – Published: 2022-05-24 19:09 – Updated: 2022-05-24 19:09In NCH Quorum v2.03 and earlier, an authenticated user can use directory traversal via logprop?file=/.. for file reading.
{
"affected": [],
"aliases": [
"CVE-2021-37445"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2021-07-25T22:15:00Z",
"severity": "MODERATE"
},
"details": "In NCH Quorum v2.03 and earlier, an authenticated user can use directory traversal via logprop?file=/.. for file reading.",
"id": "GHSA-6c69-w7wc-qm57",
"modified": "2022-05-24T19:09:15Z",
"published": "2022-05-24T19:09:15Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-37445"
},
{
"type": "WEB",
"url": "https://github.com/0xfml/poc/blob/main/NCH/Quorum_2.03_LFI.md"
},
{
"type": "WEB",
"url": "https://www.nch.com.au/conference/index.html"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-6C75-R9XF-MW95
Vulnerability from github – Published: 2022-05-02 06:17 – Updated: 2022-05-02 06:17Directory traversal vulnerability in the CARTwebERP (com_cartweberp) component 1.56.75 for Joomla! allows remote attackers to read arbitrary files via a .. (dot dot) in the controller parameter to index.php.
{
"affected": [],
"aliases": [
"CVE-2010-0982"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2010-03-16T19:30:00Z",
"severity": "MODERATE"
},
"details": "Directory traversal vulnerability in the CARTwebERP (com_cartweberp) component 1.56.75 for Joomla! allows remote attackers to read arbitrary files via a .. (dot dot) in the controller parameter to index.php.",
"id": "GHSA-6c75-r9xf-mw95",
"modified": "2022-05-02T06:17:49Z",
"published": "2022-05-02T06:17:49Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2010-0982"
},
{
"type": "WEB",
"url": "http://osvdb.org/61447"
},
{
"type": "WEB",
"url": "http://packetstormsecurity.org/1001-exploits/joomlacartweberp-lfi.txt"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/37917"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/37581"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-6C8G-7P36-R338
Vulnerability from github – Published: 2026-05-08 23:50 – Updated: 2026-07-21 20:10Summary
A path traversal vulnerability in IArchive.WriteToDirectory() allows a malicious archive to create directories outside the intended extraction root. For TAR archives, this can be escalated to arbitrary file writes by chaining with a symlink entry, giving a full write primitive on the target filesystem subject to the permissions of the running process.
Details
The vulnerable code is in the directory-entry branch of WriteToDirectoryInternal (sync, IArchiveExtensions.cs:48–61) and WriteToDirectoryAsyncInternal (async, IAsyncArchiveExtensions.cs:70–84):
var dirPath = Path.Combine(destinationDirectory, entry.Key);
Directory.CreateDirectory(Path.GetDirectoryName(dirPath + "/"));
No Path.GetFullPath() normalisation and no bounds check are applied before the Directory.CreateDirectory call. Two .NET Path.Combine behaviours make this exploitable:
- Relative traversal:
Path.Combine("/safe/extract", "../../evil")→ the OS resolves..segments on the raw path, placing the directory outside the extraction root. - Absolute path override:
Path.Combine("/safe/extract", "/tmp/evil")→ returns"/tmp/evil"— the base is discarded entirely for rooted paths.
File entries are not directly affected — they route through ExtractionMethods.WriteEntryToDirectory which applies the correct guard (GetFullPath + StartsWith, see ExtractionMethods.cs:54–65). The directory-entry branch is a separate fast-path that was added without that guard.
Affected archive formats: ZIP and TAR (non-solid). Solid archives and 7-Zip use the reader path which calls the secure method.
Escalation to arbitrary file writes (TAR only)
Path.GetFullPath on .NET does not resolve symlinks — it only normalises . and .. segments. This means the file-entry guard in ExtractionMethods.WriteEntryToDirectory can be bypassed via symlink chaining in TAR archives when the caller supplies a SymbolicLinkHandler:
archive.WriteToDirectory("/safe/extract", new ExtractionOptions
{
ExtractFullPath = true,
SymbolicLinkHandler = (linkPath, linkTarget) =>
File.CreateSymbolicLink(linkPath, linkTarget) // naive — no validation of linkTarget
});
Attack sequence in a single TAR archive:
-
Symlink entry —
link→../evil_outside/TheSymbolicLinkHandlercreates/safe/extract/linkpointing outside the extraction root. -
File entry —
link/secret.txtExtractionMethods.WriteEntryToDirectorycomputes: destdir = Path.GetFullPath("/safe/extract/link")→"/safe/extract/link"— textually inside root, check passes ✓File.Open("/safe/extract/link/secret.txt")— OS follows symlink, file is written to/evil_outside/secret.txt
The library does not validate linkTarget before passing it to the caller's handler, and the XML docs do not warn that it may be a traversal path. The idiomatic handler implementation above is therefore silently exploitable.
ZIP does not support symlinks in SharpCompress (ZipEntry.LinkTarget always returns null), so this escalation is TAR-only.
| Attack | ZIP | TAR |
|---|---|---|
| Directory traversal (escape extraction root) | Yes | Yes |
| Escalate to arbitrary file writes via symlink chain | No | Yes (if caller provides SymbolicLinkHandler) |
Recommended fix — apply the same pattern from ExtractionMethods.WriteEntryToDirectory to both affected files:
var fullDestDir = Path.GetFullPath(destinationDirectory);
if (!fullDestDir.EndsWith(Path.DirectorySeparatorChar))
fullDestDir += Path.DirectorySeparatorChar;
var dirPath = Path.GetFullPath(Path.Combine(fullDestDir, entry.Key));
if (!dirPath.StartsWith(fullDestDir, PathComparison))
throw new ExtractionException(
"Entry is trying to create a directory outside of the destination directory.");
Directory.CreateDirectory(dirPath);
Additionally, the library should validate LinkTarget before invoking the caller's SymbolicLinkHandler, or document clearly that callers must validate it themselves.
PoC
A self-contained .NET console app is available at:
https://github.com/svenclaesson/poc-sharpcompress-traversal
git clone https://github.com/svenclaesson/poc-sharpcompress-traversal
cd poc-sharpcompress-traversal
dotnet run
The PoC crafts a ZIP with three directory entries (../../escaped_relative/, /tmp/escaped_absolute/, safe_subdir/) using System.IO.Compression (stdlib), then extracts with SharpCompress. Output shows [ESCAPED] for the two malicious entries and [ok] for the legitimate one, on both sync and async APIs.
Tested against SharpCompress 0.47.4 (latest NuGet).
Impact
This is a path traversal / zip slip vulnerability (CWE-22). Any application that calls archive.WriteToDirectory() on an untrusted archive is affected — which covers the primary documented extraction API.
For ZIP archives the impact is limited to arbitrary directory creation, which can be used to stage privilege escalation (e.g. cron drop-ins, XDG config paths, service spool directories) or shadow expected paths to alter application behaviour.
For TAR archives, callers that implement a SymbolicLinkHandler — which is the only way to faithfully restore a TAR — are exposed to a full arbitrary file write primitive via the symlink chaining described above.
{
"affected": [
{
"package": {
"ecosystem": "NuGet",
"name": "SharpCompress"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.48.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-44788"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-08T23:50:40Z",
"nvd_published_at": "2026-05-26T22:16:42Z",
"severity": "MODERATE"
},
"details": "### Summary\n\nA path traversal vulnerability in `IArchive.WriteToDirectory()` allows a malicious archive to create directories outside the intended extraction root. For TAR archives, this can be escalated to arbitrary file writes by chaining with a symlink entry, giving a full write primitive on the target filesystem subject to the permissions of the running process.\n\n### Details\n\nThe vulnerable code is in the directory-entry branch of `WriteToDirectoryInternal` (sync, `IArchiveExtensions.cs:48\u201361`) and `WriteToDirectoryAsyncInternal` (async, `IAsyncArchiveExtensions.cs:70\u201384`):\n\n```csharp\nvar dirPath = Path.Combine(destinationDirectory, entry.Key);\nDirectory.CreateDirectory(Path.GetDirectoryName(dirPath + \"/\"));\n```\n\nNo `Path.GetFullPath()` normalisation and no bounds check are applied before the `Directory.CreateDirectory` call. Two .NET `Path.Combine` behaviours make this exploitable:\n\n- **Relative traversal**: `Path.Combine(\"/safe/extract\", \"../../evil\")` \u2192 the OS resolves `..` segments on the raw path, placing the directory outside the extraction root.\n- **Absolute path override**: `Path.Combine(\"/safe/extract\", \"/tmp/evil\")` \u2192 returns `\"/tmp/evil\"` \u2014 the base is discarded entirely for rooted paths.\n\nFile entries are **not** directly affected \u2014 they route through `ExtractionMethods.WriteEntryToDirectory` which applies the correct guard (`GetFullPath` + `StartsWith`, see `ExtractionMethods.cs:54\u201365`). The directory-entry branch is a separate fast-path that was added without that guard.\n\nAffected archive formats: ZIP and TAR (non-solid). Solid archives and 7-Zip use the reader path which calls the secure method.\n\n#### Escalation to arbitrary file writes (TAR only)\n\n`Path.GetFullPath` on .NET does not resolve symlinks \u2014 it only normalises `.` and `..` segments. This means the file-entry guard in `ExtractionMethods.WriteEntryToDirectory` can be bypassed via symlink chaining in TAR archives when the caller supplies a `SymbolicLinkHandler`:\n\n```csharp\narchive.WriteToDirectory(\"/safe/extract\", new ExtractionOptions\n{\n ExtractFullPath = true,\n SymbolicLinkHandler = (linkPath, linkTarget) =\u003e\n File.CreateSymbolicLink(linkPath, linkTarget) // naive \u2014 no validation of linkTarget\n});\n```\n\nAttack sequence in a single TAR archive:\n\n1. **Symlink entry** \u2014 `link` \u2192 `../evil_outside/`\n The `SymbolicLinkHandler` creates `/safe/extract/link` pointing outside the extraction root.\n\n2. **File entry** \u2014 `link/secret.txt`\n `ExtractionMethods.WriteEntryToDirectory` computes:\n - `destdir = Path.GetFullPath(\"/safe/extract/link\")` \u2192 `\"/safe/extract/link\"` \u2014 textually inside root, check passes \u2713\n - `File.Open(\"/safe/extract/link/secret.txt\")` \u2014 OS follows symlink, file is written to `/evil_outside/secret.txt`\n\nThe library does not validate `linkTarget` before passing it to the caller\u0027s handler, and the XML docs do not warn that it may be a traversal path. The idiomatic handler implementation above is therefore silently exploitable.\n\nZIP does not support symlinks in SharpCompress (`ZipEntry.LinkTarget` always returns `null`), so this escalation is TAR-only.\n\n| Attack | ZIP | TAR |\n|--------|-----|-----|\n| Directory traversal (escape extraction root) | Yes | Yes |\n| Escalate to arbitrary file writes via symlink chain | No | Yes (if caller provides `SymbolicLinkHandler`) |\n\n**Recommended fix** \u2014 apply the same pattern from `ExtractionMethods.WriteEntryToDirectory` to both affected files:\n\n```csharp\nvar fullDestDir = Path.GetFullPath(destinationDirectory);\nif (!fullDestDir.EndsWith(Path.DirectorySeparatorChar))\n fullDestDir += Path.DirectorySeparatorChar;\n\nvar dirPath = Path.GetFullPath(Path.Combine(fullDestDir, entry.Key));\nif (!dirPath.StartsWith(fullDestDir, PathComparison))\n throw new ExtractionException(\n \"Entry is trying to create a directory outside of the destination directory.\");\n\nDirectory.CreateDirectory(dirPath);\n```\n\nAdditionally, the library should validate `LinkTarget` before invoking the caller\u0027s `SymbolicLinkHandler`, or document clearly that callers must validate it themselves.\n\n### PoC\n\nA self-contained .NET console app is available at:\n`https://github.com/svenclaesson/poc-sharpcompress-traversal`\n\n```\ngit clone https://github.com/svenclaesson/poc-sharpcompress-traversal\ncd poc-sharpcompress-traversal\ndotnet run\n```\n\nThe PoC crafts a ZIP with three directory entries (`../../escaped_relative/`, `/tmp/escaped_absolute/`, `safe_subdir/`) using `System.IO.Compression` (stdlib), then extracts with SharpCompress. Output shows `[ESCAPED]` for the two malicious entries and `[ok]` for the legitimate one, on both sync and async APIs.\n\nTested against SharpCompress 0.47.4 (latest NuGet).\n\n### Impact\n\nThis is a path traversal / zip slip vulnerability (CWE-22). Any application that calls `archive.WriteToDirectory()` on an untrusted archive is affected \u2014 which covers the primary documented extraction API.\n\nFor ZIP archives the impact is limited to arbitrary directory creation, which can be used to stage privilege escalation (e.g. cron drop-ins, XDG config paths, service spool directories) or shadow expected paths to alter application behaviour.\n\nFor TAR archives, callers that implement a `SymbolicLinkHandler` \u2014 which is the only way to faithfully restore a TAR \u2014 are exposed to a full arbitrary file write primitive via the symlink chaining described above.",
"id": "GHSA-6c8g-7p36-r338",
"modified": "2026-07-21T20:10:23Z",
"published": "2026-05-08T23:50:40Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/adamhathcock/sharpcompress/security/advisories/GHSA-6c8g-7p36-r338"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44788"
},
{
"type": "WEB",
"url": "https://github.com/adamhathcock/sharpcompress/commit/2021a06626d0555a4d69471386e763ca5f5d5dfb"
},
{
"type": "PACKAGE",
"url": "https://github.com/adamhathcock/sharpcompress"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:L",
"type": "CVSS_V3"
}
],
"summary": "SharpCompress has directory traversal via directory entries in WriteToDirectory (zip slip variant)"
}
GHSA-6C8R-RP57-8JC3
Vulnerability from github – Published: 2022-05-01 23:30 – Updated: 2022-05-01 23:30Directory traversal vulnerability in file.php in bloofoxCMS 0.3 allows remote attackers to read arbitrary files via a .. (dot dot) in the file parameter.
{
"affected": [],
"aliases": [
"CVE-2008-0427"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2008-01-23T22:00:00Z",
"severity": "HIGH"
},
"details": "Directory traversal vulnerability in file.php in bloofoxCMS 0.3 allows remote attackers to read arbitrary files via a .. (dot dot) in the file parameter.",
"id": "GHSA-6c8r-rp57-8jc3",
"modified": "2022-05-01T23:30:10Z",
"published": "2022-05-01T23:30:10Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2008-0427"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/39795"
},
{
"type": "WEB",
"url": "https://www.exploit-db.com/exploits/4945"
},
{
"type": "WEB",
"url": "http://bugreport.ir/?/27"
},
{
"type": "WEB",
"url": "http://marc.info/?l=bugtraq\u0026m=120093005310107\u0026w=2"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/28415"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/archive/1/486714/100/0/threaded"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/27361"
},
{
"type": "WEB",
"url": "http://www.vupen.com/english/advisories/2008/0218"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-6CC4-G986-CX7V
Vulnerability from github – Published: 2022-05-01 23:50 – Updated: 2025-04-09 03:58Directory traversal vulnerability in the UpdateAgent function in TmListen.exe in the OfficeScanNT Listener service in the client in Trend Micro OfficeScan 7.3 Patch 4 build 1367 and other builds before 1372, OfficeScan 8.0 SP1 before build 1222, OfficeScan 8.0 SP1 Patch 1 before build 3087, and Worry-Free Business Security 5.0 before build 1220 allows remote attackers to read arbitrary files via directory traversal sequences in an HTTP request. NOTE: some of these details are obtained from third party information.
{
"affected": [],
"aliases": [
"CVE-2008-2439"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2008-10-03T15:07:00Z",
"severity": "MODERATE"
},
"details": "Directory traversal vulnerability in the UpdateAgent function in TmListen.exe in the OfficeScanNT Listener service in the client in Trend Micro OfficeScan 7.3 Patch 4 build 1367 and other builds before 1372, OfficeScan 8.0 SP1 before build 1222, OfficeScan 8.0 SP1 Patch 1 before build 3087, and Worry-Free Business Security 5.0 before build 1220 allows remote attackers to read arbitrary files via directory traversal sequences in an HTTP request. NOTE: some of these details are obtained from third party information.",
"id": "GHSA-6cc4-g986-cx7v",
"modified": "2025-04-09T03:58:59Z",
"published": "2022-05-01T23:50:02Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2008-2439"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/45597"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/31343"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/32097"
},
{
"type": "WEB",
"url": "http://secunia.com/secunia_research/2008-39"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/archive/1/496970/100/0/threaded"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/31531"
},
{
"type": "WEB",
"url": "http://www.securitytracker.com/id?1020975"
},
{
"type": "WEB",
"url": "http://www.trendmicro.com/ftp/documentation/readme/OSCE8.0_SP1_Patch1_CriticalPatch_3087_Readme.txt"
},
{
"type": "WEB",
"url": "http://www.trendmicro.com/ftp/documentation/readme/OSCE_7.3_Win_EN_CriticalPatch_B1372_Readme.txt"
},
{
"type": "WEB",
"url": "http://www.trendmicro.com/ftp/documentation/readme/OSCE_8.0_SP1_Win_EN_CriticalPatch_B2439_Readme.txt"
},
{
"type": "WEB",
"url": "http://www.trendmicro.com/ftp/documentation/readme/Readme_WFBS5.0_EN_CriticalPatch1414.txt"
},
{
"type": "WEB",
"url": "http://www.vupen.com/english/advisories/2008/2711"
},
{
"type": "WEB",
"url": "http://www.vupen.com/english/advisories/2008/2712"
}
],
"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.