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.
13217 vulnerabilities reference this CWE, most recent first.
GHSA-693V-3VGH-6XPH
Vulnerability from github – Published: 2023-09-06 15:30 – Updated: 2024-04-04 07:31Acrobat Reader DC versions 2021.005.20054 (and earlier), 2020.004.30005 (and earlier) and 2017.011.30197 (and earlier) are affected by a Path traversal vulnerability. An unauthenticated attacker could leverage this vulnerability to achieve arbitrary code execution in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.
{
"affected": [],
"aliases": [
"CVE-2021-28644"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-09-06T14:15:08Z",
"severity": "HIGH"
},
"details": "Acrobat Reader DC versions 2021.005.20054 (and earlier), 2020.004.30005 (and earlier) and 2017.011.30197 (and earlier) are affected by a Path traversal vulnerability. An unauthenticated attacker could leverage this vulnerability to achieve arbitrary code execution in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.",
"id": "GHSA-693v-3vgh-6xph",
"modified": "2024-04-04T07:31:57Z",
"published": "2023-09-06T15:30:26Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-28644"
},
{
"type": "WEB",
"url": "https://helpx.adobe.com/security/products/acrobat/apsb21-51.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-693W-MP32-8PWQ
Vulnerability from github – Published: 2022-05-14 03:38 – Updated: 2022-05-14 03:38In Apache Allura before 1.8.0, unauthenticated attackers may retrieve arbitrary files through the Allura web application. Some webservers used with Allura, such as Nginx, Apache/mod_wsgi or paster may prevent the attack from succeeding. Others, such as gunicorn do not prevent it and leave Allura vulnerable.
{
"affected": [],
"aliases": [
"CVE-2018-1299"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2018-02-06T20:29:00Z",
"severity": "HIGH"
},
"details": "In Apache Allura before 1.8.0, unauthenticated attackers may retrieve arbitrary files through the Allura web application. Some webservers used with Allura, such as Nginx, Apache/mod_wsgi or paster may prevent the attack from succeeding. Others, such as gunicorn do not prevent it and leave Allura vulnerable.",
"id": "GHSA-693w-mp32-8pwq",
"modified": "2022-05-14T03:38:29Z",
"published": "2022-05-14T03:38:29Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2018-1299"
},
{
"type": "WEB",
"url": "https://allura.apache.org/posts/2018-allura-1.8.0.html"
},
{
"type": "WEB",
"url": "https://lists.apache.org/thread.html/b52069073cf3cb0f84c9e1e2b34d411fc163af39e4f3e50712ac8a4d@%3Cdev.allura.apache.org%3E"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-694V-63FQ-FMR4
Vulnerability from github – Published: 2022-05-04 00:00 – Updated: 2022-05-18 19:57Scout is a Variant Call Format (VCF) visualization interface. The Pypi package scout-browser is vulnerable to path traversal due to send_file call in versions prior to 4.52.
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "scout-browser"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "4.52"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2022-1554"
],
"database_specific": {
"cwe_ids": [
"CWE-22",
"CWE-36"
],
"github_reviewed": true,
"github_reviewed_at": "2022-05-18T19:57:37Z",
"nvd_published_at": "2022-05-03T09:15:00Z",
"severity": "MODERATE"
},
"details": "Scout is a Variant Call Format (VCF) visualization interface. The Pypi package `scout-browser` is vulnerable to path traversal due to `send_file` call in versions prior to 4.52.",
"id": "GHSA-694v-63fq-fmr4",
"modified": "2022-05-18T19:57:37Z",
"published": "2022-05-04T00:00:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-1554"
},
{
"type": "WEB",
"url": "https://github.com/Clinical-Genomics/scout/issues/3128"
},
{
"type": "WEB",
"url": "https://github.com/Clinical-Genomics/scout/issues/3302"
},
{
"type": "WEB",
"url": "https://github.com/Clinical-Genomics/scout/pull/3303"
},
{
"type": "WEB",
"url": "https://github.com/clinical-genomics/scout/commit/952a2e2319af2d95d22b017a561730feac086ff1"
},
{
"type": "PACKAGE",
"url": "https://github.com/clinical-genomics/scout"
},
{
"type": "WEB",
"url": "https://huntr.dev/bounties/7acac778-5ba4-4f02-99e2-e4e17a81e600"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:H/A:L",
"type": "CVSS_V3"
}
],
"summary": "Path Traversal in scout-browser"
}
GHSA-695G-CV7C-9P7X
Vulnerability from github – Published: 2023-02-13 15:30 – Updated: 2023-02-21 21:30The Customer Reviews for WooCommerce WordPress plugin before 5.16.0 does not validate one of its shortcode attribute, which could allow users with a contributor role and above to include arbitrary files via a traversal attack. This could also allow them to read non PHP files and retrieve their content. RCE could also be achieved if the attacker manage to upload a malicious image containing PHP code, and then include it via the affected attribute, on a default WP install, authors could easily achieve that given that they have the upload_file capability.
{
"affected": [],
"aliases": [
"CVE-2023-0080"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-02-13T15:15:00Z",
"severity": "HIGH"
},
"details": "The Customer Reviews for WooCommerce WordPress plugin before 5.16.0 does not validate one of its shortcode attribute, which could allow users with a contributor role and above to include arbitrary files via a traversal attack. This could also allow them to read non PHP files and retrieve their content. RCE could also be achieved if the attacker manage to upload a malicious image containing PHP code, and then include it via the affected attribute, on a default WP install, authors could easily achieve that given that they have the upload_file capability.",
"id": "GHSA-695g-cv7c-9p7x",
"modified": "2023-02-21T21:30:17Z",
"published": "2023-02-13T15:30:25Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-0080"
},
{
"type": "WEB",
"url": "https://wpscan.com/vulnerability/6b0d63ed-e244-4f20-8f10-a6e0c7ccadd4"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-696V-J6JG-M6W8
Vulnerability from github – Published: 2022-12-22 21:30 – Updated: 2022-12-28 15:30IBM Navigator for i 7.3, 7.4 and 7.5 could allow an authenticated user to access IBM Navigator for i log files they are authorized to but not while using this interface. The remote authenticated user can bypass the interface checks and download log files by modifying servlet filter. IBM X-Force ID: 239301.
{
"affected": [],
"aliases": [
"CVE-2022-43857"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-12-22T21:15:00Z",
"severity": "MODERATE"
},
"details": "IBM Navigator for i 7.3, 7.4 and 7.5 could allow an authenticated user to access IBM Navigator for i log files they are authorized to but not while using this interface. The remote authenticated user can bypass the interface checks and download log files by modifying servlet filter. IBM X-Force ID: 239301.",
"id": "GHSA-696v-j6jg-m6w8",
"modified": "2022-12-28T15:30:46Z",
"published": "2022-12-22T21:30:26Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-43857"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/239301"
},
{
"type": "WEB",
"url": "https://www.ibm.com/support/pages/node/6850801"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-699J-C85P-XV8W
Vulnerability from github – Published: 2025-08-22 21:31 – Updated: 2025-08-27 15:33Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in Salesforce Tableau Server on Windows, Linux (abdoc api - create-data-source-from-file-upload modules) allows Absolute Path Traversal.This issue affects Tableau Server: before 2025.1.3, before 2024.2.12, before 2023.3.19.
{
"affected": [],
"aliases": [
"CVE-2025-52450"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-08-22T21:15:32Z",
"severity": "MODERATE"
},
"details": "Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027) vulnerability in Salesforce Tableau Server on Windows, Linux (abdoc api - create-data-source-from-file-upload modules) allows Absolute Path Traversal.This issue affects Tableau Server: before 2025.1.3, before 2024.2.12, before 2023.3.19.",
"id": "GHSA-699j-c85p-xv8w",
"modified": "2025-08-27T15:33:13Z",
"published": "2025-08-22T21:31:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-52450"
},
{
"type": "WEB",
"url": "https://help.salesforce.com/s/articleView?id=005132575\u0026type=1"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-699M-4V95-RMPM
Vulnerability from github – Published: 2026-02-13 16:16 – Updated: 2026-02-13 22:11Summary
Two path traversal vulnerabilities in the local block adapter allow authenticated users to read and write files outside their designated storage boundaries.
Details
The local block adapter in pkg/block/local/adapter.go had two path traversal vulnerabilities:
1. Prefix Bypass Vulnerability
The verifyRelPath function used strings.HasPrefix() to verify that requested paths fall within the configured storage directory. This check was insufficient because it validated only the path prefix without requiring a path separator, allowing access to sibling directories with similar names.
Example: If the adapter is configured with base path /data/lakefs:
| Path | Expected | Actual |
|---|---|---|
/data/lakefs/valid/file.txt |
Allowed | Allowed |
/data/lakefs_evil/secret.txt |
Blocked | Vulnerable |
/data/lakefs_backup/data.db |
Blocked | Vulnerable |
2. Namespace Escape via Identifier
The adapter verified that resolved paths stayed within the adapter's base path, but did not verify that object identifiers stayed within their designated storage namespace. This allowed attackers to use path traversal sequences in the object identifier to access files in other namespaces.
Example: With base path /data/lakefs and namespace local://repo1/userdata:
| Identifier | Resolved Path | Expected | Actual |
|---|---|---|---|
file.txt |
/data/lakefs/repo1/userdata/file.txt |
Allowed | Allowed |
../secrets/key.txt |
/data/lakefs/repo1/secrets/key.txt |
Blocked | Vulnerable |
../../other-repo/data.txt |
/data/lakefs/other-repo/data.txt |
Blocked | Vulnerable |
This vulnerability allows users with access to one namespace to read and write files in other namespaces within the same lakeFS deployment.
Impact
Authenticated lakeFS users can:
- Read and write files in sibling directories that share the same path prefix as the storage directory (vulnerability 1)
- Access files across namespaces by using path traversal in object identifiers (vulnerability 2)
This could allow attackers to:
- Read sensitive data from other repositories/namespaces
- Write malicious files to other namespaces
- Read/write files in adjacent directories outside lakeFS storage
- Potentially escalate privileges if writable directories are used by other services
This vulnerability only affects deployments using the local block adapter. Deployments using S3, GCS, Azure, or other object storage backends are not affected.
Patches
Fixed in version v1.77.0.
The fixes: 1. Append a path separator to prefix checks, ensuring paths must be within the storage directory 2. Add two-level path validation: verify both that namespace paths stay within the adapter's base path AND that resolved paths stay within their designated namespace
Workarounds
- Configure the storage path with a unique name unlikely to be a prefix of other directories
- Restrict filesystem permissions for the lakeFS process
- Ensure no sensitive data exists in sibling directories
Credit
Discovered via CodeQL static analysis.
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 1.76.0"
},
"package": {
"ecosystem": "Go",
"name": "github.com/treeverse/lakefs"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.77.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-26187"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2026-02-13T16:16:04Z",
"nvd_published_at": "2026-02-13T19:17:29Z",
"severity": "HIGH"
},
"details": "## Summary\n\nTwo path traversal vulnerabilities in the local block adapter allow authenticated users to read and write files outside their designated storage boundaries.\n\n## Details\n\nThe local block adapter in `pkg/block/local/adapter.go` had two path traversal vulnerabilities:\n\n### 1. Prefix Bypass Vulnerability\n\nThe `verifyRelPath` function used `strings.HasPrefix()` to verify that requested paths fall within the configured storage directory. This check was insufficient because it validated only the path prefix without requiring a path separator, allowing access to sibling directories with similar names.\n\n**Example:** If the adapter is configured with base path `/data/lakefs`:\n\n| Path | Expected | Actual |\n|------|----------|--------|\n| `/data/lakefs/valid/file.txt` | Allowed | Allowed |\n| `/data/lakefs_evil/secret.txt` | Blocked | **Vulnerable** |\n| `/data/lakefs_backup/data.db` | Blocked | **Vulnerable** |\n\n### 2. Namespace Escape via Identifier\n\nThe adapter verified that resolved paths stayed within the adapter\u0027s base path, but did not verify that object identifiers stayed within their designated storage namespace. This allowed attackers to use path traversal sequences in the object identifier to access files in other namespaces.\n\n**Example:** With base path `/data/lakefs` and namespace `local://repo1/userdata`:\n\n| Identifier | Resolved Path | Expected | Actual |\n|------------|---------------|----------|--------|\n| `file.txt` | `/data/lakefs/repo1/userdata/file.txt` | Allowed | Allowed |\n| `../secrets/key.txt` | `/data/lakefs/repo1/secrets/key.txt` | Blocked | **Vulnerable** |\n| `../../other-repo/data.txt` | `/data/lakefs/other-repo/data.txt` | Blocked | **Vulnerable** |\n\nThis vulnerability allows users with access to one namespace to read and write files in other namespaces within the same lakeFS deployment.\n\n## Impact\n\nAuthenticated lakeFS users can:\n\n- **Read and write files in sibling directories** that share the same path prefix as the storage directory (vulnerability 1)\n- **Access files across namespaces** by using path traversal in object identifiers (vulnerability 2)\n\nThis could allow attackers to:\n\n- Read sensitive data from other repositories/namespaces\n- Write malicious files to other namespaces\n- Read/write files in adjacent directories outside lakeFS storage\n- Potentially escalate privileges if writable directories are used by other services\n\nThis vulnerability **only affects** deployments using the local block adapter. Deployments using S3, GCS, Azure, or other object storage backends are **not affected**.\n\n## Patches\n\nFixed in version v1.77.0.\n\nThe fixes:\n1. Append a path separator to prefix checks, ensuring paths must be within the storage directory\n2. Add two-level path validation: verify both that namespace paths stay within the adapter\u0027s base path AND that resolved paths stay within their designated namespace\n\n## Workarounds\n\n- Configure the storage path with a unique name unlikely to be a prefix of other directories\n- Restrict filesystem permissions for the lakeFS process\n- Ensure no sensitive data exists in sibling directories\n\n## Credit\n\nDiscovered via CodeQL static analysis.",
"id": "GHSA-699m-4v95-rmpm",
"modified": "2026-02-13T22:11:49Z",
"published": "2026-02-13T16:16:04Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/treeverse/lakeFS/security/advisories/GHSA-699m-4v95-rmpm"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-26187"
},
{
"type": "WEB",
"url": "https://github.com/treeverse/lakeFS/commit/cbc106275357302a834280f133265dc39f1384ce"
},
{
"type": "PACKAGE",
"url": "https://github.com/treeverse/lakeFS"
},
{
"type": "WEB",
"url": "https://github.com/treeverse/lakeFS/releases/tag/v1.77.0"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
"type": "CVSS_V3"
}
],
"summary": "lakeFS vulnerable to path traversal in local block adapter allow cross-namespace and sibling directory access"
}
GHSA-69GF-3XVG-XR2V
Vulnerability from github – Published: 2023-08-31 18:30 – Updated: 2023-08-31 18:30Sensitive information disclosure due to improper input validation. The following products are affected: Acronis Cloud Manager (Windows) before build 6.2.23089.203.
{
"affected": [],
"aliases": [
"CVE-2023-41747"
],
"database_specific": {
"cwe_ids": [
"CWE-20",
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-08-31T18:15:09Z",
"severity": "MODERATE"
},
"details": "Sensitive information disclosure due to improper input validation. The following products are affected: Acronis Cloud Manager (Windows) before build 6.2.23089.203.",
"id": "GHSA-69gf-3xvg-xr2v",
"modified": "2023-08-31T18:30:28Z",
"published": "2023-08-31T18:30:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-41747"
},
{
"type": "WEB",
"url": "https://security-advisory.acronis.com/advisories/SEC-5811"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-69HM-FPG2-329F
Vulnerability from github – Published: 2022-05-17 05:34 – Updated: 2022-05-17 05:34Directory traversal vulnerability in team.rc5-72.php in DNET Live-Stats 0.8 allows remote attackers to read arbitrary files via a .. (dot dot) in the showlang parameter.
{
"affected": [],
"aliases": [
"CVE-2010-4858"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2011-10-05T10:55:00Z",
"severity": "MODERATE"
},
"details": "Directory traversal vulnerability in team.rc5-72.php in DNET Live-Stats 0.8 allows remote attackers to read arbitrary files via a .. (dot dot) in the showlang parameter.",
"id": "GHSA-69hm-fpg2-329f",
"modified": "2022-05-17T05:34:14Z",
"published": "2022-05-17T05:34:14Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2010-4858"
},
{
"type": "WEB",
"url": "http://packetstormsecurity.org/1010-exploits/dnetlivestats-lfi.txt"
},
{
"type": "WEB",
"url": "http://securityreason.com/securityalert/8417"
},
{
"type": "WEB",
"url": "http://www.exploit-db.com/exploits/15204"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/43708"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-69JH-5QJP-FCX9
Vulnerability from github – Published: 2025-12-29 03:30 – Updated: 2025-12-29 03:30Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'), Missing Authorization vulnerability in Innorix WP allows Path Traversal.This issue affects Innorix WP from All versions If the "exam" directory exists under the directory where the product is installed (ex: innorix/exam)
{
"affected": [],
"aliases": [
"CVE-2025-15066"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-12-29T01:15:52Z",
"severity": "MODERATE"
},
"details": "Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027), Missing Authorization vulnerability in Innorix WP allows Path Traversal.This issue affects Innorix WP from All versions If the \"exam\" directory exists under the directory where the product is installed (ex: innorix/exam)",
"id": "GHSA-69jh-5qjp-fcx9",
"modified": "2025-12-29T03:30:24Z",
"published": "2025-12-29T03:30:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-15066"
},
{
"type": "WEB",
"url": "https://www.gnit.co.kr/software/innorix_product.html"
},
{
"type": "WEB",
"url": "https://www.innorix.com"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/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"
}
]
}
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.