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.
13175 vulnerabilities reference this CWE, most recent first.
GHSA-G79V-HXM3-34MV
Vulnerability from github – Published: 2022-05-14 02:20 – Updated: 2022-05-14 02:20/filemanager/upload.php in Responsive FileManager before 9.13.3 allows Directory Traversal and SSRF because the url parameter is used directly in a curl_exec call, as demonstrated by a file:///etc/passwd value.
{
"affected": [],
"aliases": [
"CVE-2018-15495"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2018-08-18T02:29:00Z",
"severity": "HIGH"
},
"details": "/filemanager/upload.php in Responsive FileManager before 9.13.3 allows Directory Traversal and SSRF because the url parameter is used directly in a curl_exec call, as demonstrated by a file:///etc/passwd value.",
"id": "GHSA-g79v-hxm3-34mv",
"modified": "2022-05-14T02:20:15Z",
"published": "2022-05-14T02:20:15Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2018-15495"
},
{
"type": "WEB",
"url": "https://github.com/trippo/ResponsiveFilemanager/blob/master/changelog.txt"
},
{
"type": "WEB",
"url": "http://seclists.org/fulldisclosure/2018/Aug/9"
}
],
"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-G7C3-PP5R-M3V8
Vulnerability from github – Published: 2023-08-31 18:30 – Updated: 2024-04-04 07:20Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in Schweitzer Engineering Laboratories SEL-5036 acSELerator Bay Screen Builder Software on Windows allows Relative Path Traversal.
SEL acSELerator Bay Screen Builder software is distributed by SEL-5033 SEL acSELerator RTAC, SEL-5030 Quickset, and SEL Compass. CVE-2023-31167 and was patched in the acSELerator Bay Screen Builder release available on 20230602. Please contact SEL for additional details.
This issue affects SEL-5036 acSELerator Bay Screen Builder Software: before 1.0.49152.778.
{
"affected": [],
"aliases": [
"CVE-2023-31167"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-08-31T16:15:08Z",
"severity": "HIGH"
},
"details": "Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027) vulnerability in Schweitzer Engineering Laboratories SEL-5036 acSELerator Bay Screen Builder Software on Windows allows Relative Path Traversal.\n\n\n\nSEL acSELerator Bay Screen Builder software is distributed by SEL-5033 SEL acSELerator RTAC, SEL-5030 Quickset, and SEL Compass. CVE-2023-31167 and was patched in the acSELerator Bay Screen Builder release available on 20230602. Please contact SEL for additional details.\n\n\nThis issue affects SEL-5036 acSELerator Bay Screen Builder Software: before 1.0.49152.778.\n\n",
"id": "GHSA-g7c3-pp5r-m3v8",
"modified": "2024-04-04T07:20:39Z",
"published": "2023-08-31T18:30:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-31167"
},
{
"type": "WEB",
"url": "https://dragos.com"
},
{
"type": "WEB",
"url": "https://selinc.com/support/security-notifications/external-reports"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-G7CX-36JQ-75P8
Vulnerability from github – Published: 2025-07-02 09:30 – Updated: 2025-07-02 09:30Path traversal in WebGUI HTTP endpoint in Infinera G42 version R6.1.3 allows remote authenticated users to download all OS files via HTTP requests.
Details:
Lack or insufficient validation of user-supplied input allows authenticated users to access all files on the target machine file system that are readable to the user account used to run the httpd service.
{
"affected": [],
"aliases": [
"CVE-2025-27022"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-07-02T09:15:25Z",
"severity": "HIGH"
},
"details": "Path traversal in WebGUI HTTP endpoint in Infinera G42 version R6.1.3 \nallows remote authenticated users to download all OS files via HTTP \nrequests.\n\n\nDetails: \n\nLack or insufficient validation of user-supplied input allows \nauthenticated users to access all files on the target machine file \nsystem that are readable to the user account used to run the httpd \nservice.",
"id": "GHSA-g7cx-36jq-75p8",
"modified": "2025-07-02T09:30:29Z",
"published": "2025-07-02T09:30:29Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-27022"
},
{
"type": "WEB",
"url": "https://euvd.enisa.europa.eu/vulnerability/CVE-2025-27022"
},
{
"type": "WEB",
"url": "https://www.cvcn.gov.it/cvcn/cve/CVE-2025-27022"
}
],
"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-G7GQ-QMH4-JHWW
Vulnerability from github – Published: 2026-01-22 18:30 – Updated: 2026-01-27 21:31Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in AivahThemes Anona anona allows Path Traversal.This issue affects Anona: from n/a through <= 8.0.
{
"affected": [],
"aliases": [
"CVE-2025-68902"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-01-22T17:16:13Z",
"severity": "HIGH"
},
"details": "Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027) vulnerability in AivahThemes Anona anona allows Path Traversal.This issue affects Anona: from n/a through \u003c= 8.0.",
"id": "GHSA-g7gq-qmh4-jhww",
"modified": "2026-01-27T21:31:41Z",
"published": "2026-01-22T18:30:36Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-68902"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/Wordpress/Theme/anona/vulnerability/wordpress-anona-theme-8-0-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:L/I:L/A:L",
"type": "CVSS_V3"
}
]
}
GHSA-G7H7-RG53-H2G9
Vulnerability from github – Published: 2022-07-12 00:00 – Updated: 2022-07-16 00:00The RipudamanKaushikDal/projects repository through 2022-04-03 on GitHub allows absolute path traversal because the Flask send_file function is used unsafely.
{
"affected": [],
"aliases": [
"CVE-2022-31569"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-07-11T01:15:00Z",
"severity": "CRITICAL"
},
"details": "The RipudamanKaushikDal/projects repository through 2022-04-03 on GitHub allows absolute path traversal because the Flask send_file function is used unsafely.",
"id": "GHSA-g7h7-rg53-h2g9",
"modified": "2022-07-16T00:00:28Z",
"published": "2022-07-12T00:00:58Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-31569"
},
{
"type": "WEB",
"url": "https://github.com/github/securitylab/issues/669#issuecomment-1117265726"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:L",
"type": "CVSS_V3"
}
]
}
GHSA-G7J3-P357-CW8P
Vulnerability from github – Published: 2018-07-24 16:29 – Updated: 2023-09-13 20:24Affected versions of f2e-server resolve relative file paths, resulting in a directory traversal vulnerability. A malicious actor can use this vulnerability to access files outside of the intended directory root, which may result in the disclosure of private files on the vulnerable system.
Example request:
GET /../../../../../../../../../../etc/passwd HTTP/1.1
host:foo
Recommendation
Update to version 1.12.12 or later.
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 1.12.11"
},
"package": {
"ecosystem": "npm",
"name": "f2e-server"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.12.12"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2017-16038"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2020-06-16T21:36:17Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "Affected versions of `f2e-server` resolve relative file paths, resulting in a directory traversal vulnerability. A malicious actor can use this vulnerability to access files outside of the intended directory root, which may result in the disclosure of private files on the vulnerable system.\n\n**Example request:**\n```http\nGET /../../../../../../../../../../etc/passwd HTTP/1.1\nhost:foo\n```\n\n\n## Recommendation\n\nUpdate to version 1.12.12 or later.",
"id": "GHSA-g7j3-p357-cw8p",
"modified": "2023-09-13T20:24:14Z",
"published": "2018-07-24T16:29:12Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2017-16038"
},
{
"type": "WEB",
"url": "https://github.com/shy2850/node-server/issues/10"
},
{
"type": "WEB",
"url": "https://github.com/shy2850/node-server/pull/12/files"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-g7j3-p357-cw8p"
},
{
"type": "PACKAGE",
"url": "https://github.com/shy2850/node-server"
},
{
"type": "WEB",
"url": "https://www.npmjs.com/advisories/346"
}
],
"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"
}
],
"summary": "Directory Traversal in f2e-server"
}
GHSA-G7QV-MXMC-4X8H
Vulnerability from github – Published: 2022-05-14 02:58 – Updated: 2022-05-14 02:58Open Networking Foundation (ONF) ONOS version 1.13.2 and earlier version contains a Directory Traversal vulnerability in core/common/src/main/java/org/onosproject/common/app/ApplicationArchive.java line 35 that can result in arbitrary file deletion (overwrite). This attack appear to be exploitable via a specially crafted zip file should be uploaded.
{
"affected": [],
"aliases": [
"CVE-2018-1999020"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2018-07-23T15:29:00Z",
"severity": "MODERATE"
},
"details": "Open Networking Foundation (ONF) ONOS version 1.13.2 and earlier version contains a Directory Traversal vulnerability in core/common/src/main/java/org/onosproject/common/app/ApplicationArchive.java line 35 that can result in arbitrary file deletion (overwrite). This attack appear to be exploitable via a specially crafted zip file should be uploaded.",
"id": "GHSA-g7qv-mxmc-4x8h",
"modified": "2022-05-14T02:58:55Z",
"published": "2022-05-14T02:58:55Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2018-1999020"
},
{
"type": "WEB",
"url": "https://gerrit.onosproject.org/#/c/19043"
},
{
"type": "WEB",
"url": "http://gms.cl0udz.com/ONOS_app_overwrite.pdf"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-G7R4-M6W7-QQQR
Vulnerability from github – Published: 2026-06-12 20:08 – Updated: 2026-06-12 20:08Summary
The development server contains a path traversal vulnerability on Windows when serving files from servedir.
Due to the use of path.Clean() (which only normalizes forward-slash / separators) instead of a Windows-aware path normalization function, it is possible to craft requests using backslashes (\) that bypass the intended directory containment logic. An attacker can escape the configured servedir root and access arbitrary files on the filesystem.
This issue affects Windows environments only.
Details
The request path is sanitized using:
// https://github.com/evanw/esbuild/blob/v0.27.3/pkg/api/serve_other.go#L165
queryPath := path.Clean(req.URL.Path)[1:]
However:
- path.Clean() is POSIX-style and only understands / (docs: https://pkg.go.dev/path#Clean)
- On Windows, \ is a valid path separator
- path.Clean() does not treat \ as a separator
Later, the server constructs the absolute path:
// https://github.com/evanw/esbuild/blob/v0.27.3/pkg/api/serve_other.go#L221
absPath := h.fs.Join(h.servedir, queryPath)
If queryPath contains sequences such as:
..\..\..\..\..\..\..\Windows\system.ini
path.Clean() will not normalize them, but the Windows filesystem will interpret \ as directory separators when resolving absPath.
Because the implementation does not verify that the final resolved path remains within servedir, it allows directory traversal outside the intended root directory.
Vulnerable Code
// https://github.com/evanw/esbuild/blob/v0.27.3/pkg/api/serve_other.go#L165
queryPath := path.Clean(req.URL.Path)[1:]
....
// Check for a file in the "servedir" directory
if h.servedir != "" && kind != fs.FileEntry {
absPath := h.fs.Join(h.servedir, queryPath)
if absDir := h.fs.Dir(absPath); absDir != absPath {
if entries, err, _ := h.fs.ReadDirectory(absDir); err == nil {
if entry, _ := entries.Get(h.fs.Base(absPath)); entry != nil && entry.Kind(h.fs) == fs.FileEntry {
....
Steps to reproduce
npm install --save-exact --save-dev esbuild
echo "console.log(1)" > app.js
.\node_modules\.bin\esbuild --version
0.27.3
.\node_modules\.bin\esbuild app.js --bundle --outdir=www --servedir=www --watch
curl -i --path-as-is "http://localhost:8000/..\..\..\..\..\..\..\Windows\system.ini"
<content of Windows\system.ini>
Impact
- Arbitrary file read on Windows
- Exposure of sensitive files
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "esbuild"
},
"ranges": [
{
"events": [
{
"introduced": "0.27.3"
},
{
"fixed": "0.28.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2026-06-12T20:08:53Z",
"nvd_published_at": null,
"severity": "LOW"
},
"details": "### Summary\n\nThe development server contains a path traversal vulnerability on Windows when serving files from `servedir`.\n\nDue to the use of `path.Clean()` (which only normalizes forward-slash `/` separators) instead of a Windows-aware path normalization function, it is possible to craft requests using backslashes (`\\`) that bypass the intended directory containment logic. An attacker can escape the configured `servedir` root and access arbitrary files on the filesystem.\nThis issue affects Windows environments only.\n\n### Details\n\nThe request path is sanitized using:\n```go\n// https://github.com/evanw/esbuild/blob/v0.27.3/pkg/api/serve_other.go#L165\nqueryPath := path.Clean(req.URL.Path)[1:]\n```\n\n\nHowever:\n- `path.Clean()` is POSIX-style and only understands `/` (docs: `https://pkg.go.dev/path#Clean`)\n- On Windows, `\\` is a valid path separator\n- `path.Clean()` does not treat `\\` as a separator\n\nLater, the server constructs the absolute path:\n```go\n// https://github.com/evanw/esbuild/blob/v0.27.3/pkg/api/serve_other.go#L221\nabsPath := h.fs.Join(h.servedir, queryPath)\n```\n\nIf `queryPath` contains sequences such as:\n```\n..\\..\\..\\..\\..\\..\\..\\Windows\\system.ini\n```\n\n`path.Clean()` will not normalize them, but the Windows filesystem will interpret `\\` as directory separators when resolving `absPath`.\nBecause the implementation does not verify that the final resolved path remains within `servedir`, it allows directory traversal outside the intended root directory.\n### Vulnerable Code\n\n```go\n// https://github.com/evanw/esbuild/blob/v0.27.3/pkg/api/serve_other.go#L165\n\tqueryPath := path.Clean(req.URL.Path)[1:]\n\t....\n\t// Check for a file in the \"servedir\" directory\n\tif h.servedir != \"\" \u0026\u0026 kind != fs.FileEntry {\n\t\tabsPath := h.fs.Join(h.servedir, queryPath)\n\t\tif absDir := h.fs.Dir(absPath); absDir != absPath {\n\t\t\tif entries, err, _ := h.fs.ReadDirectory(absDir); err == nil {\n\t\t\t\tif entry, _ := entries.Get(h.fs.Base(absPath)); entry != nil \u0026\u0026 entry.Kind(h.fs) == fs.FileEntry {\n\t....\t\t\t\t\n```\n\n\n### Steps to reproduce\n\n```\nnpm install --save-exact --save-dev esbuild\n\necho \"console.log(1)\" \u003e app.js\n\n.\\node_modules\\.bin\\esbuild --version\n0.27.3\n\n.\\node_modules\\.bin\\esbuild app.js --bundle --outdir=www --servedir=www --watch\n\ncurl -i --path-as-is \"http://localhost:8000/..\\..\\..\\..\\..\\..\\..\\Windows\\system.ini\"\n\u003ccontent of Windows\\system.ini\u003e\n```\n\n\n### Impact\n\n- Arbitrary file read on Windows\n- Exposure of sensitive files",
"id": "GHSA-g7r4-m6w7-qqqr",
"modified": "2026-06-12T20:08:53Z",
"published": "2026-06-12T20:08:53Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/evanw/esbuild/security/advisories/GHSA-g7r4-m6w7-qqqr"
},
{
"type": "PACKAGE",
"url": "https://github.com/evanw/esbuild"
},
{
"type": "WEB",
"url": "https://github.com/evanw/esbuild/releases/tag/v0.28.1"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "esbuild allows arbitrary file read when running the development server on Windows"
}
GHSA-G7RF-G4J7-7FC4
Vulnerability from github – Published: 2022-06-03 00:01 – Updated: 2022-06-10 00:00The affected products are vulnerable to directory traversal, which may allow an attacker to obtain arbitrary operating system files.
{
"affected": [],
"aliases": [
"CVE-2022-1661"
],
"database_specific": {
"cwe_ids": [
"CWE-22",
"CWE-23"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-06-02T14:15:00Z",
"severity": "HIGH"
},
"details": "The affected products are vulnerable to directory traversal, which may allow an attacker to obtain arbitrary operating system files.",
"id": "GHSA-g7rf-g4j7-7fc4",
"modified": "2022-06-10T00:00:49Z",
"published": "2022-06-03T00:01:01Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-1661"
},
{
"type": "WEB",
"url": "https://www.cisa.gov/uscert/ics/advisories/icsa-22-146-01"
}
],
"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-G7RG-76WX-HFGM
Vulnerability from github – Published: 2022-05-17 02:27 – Updated: 2022-05-17 02:27get2post.php in IDERA Uptime Monitor 7.8 has directory traversal in the file_name parameter.
{
"affected": [],
"aliases": [
"CVE-2017-11469"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2017-07-20T04:29:00Z",
"severity": "HIGH"
},
"details": "get2post.php in IDERA Uptime Monitor 7.8 has directory traversal in the file_name parameter.",
"id": "GHSA-g7rg-76wx-hfgm",
"modified": "2022-05-17T02:27:10Z",
"published": "2022-05-17T02:27:10Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2017-11469"
},
{
"type": "WEB",
"url": "https://blogs.securiteam.com/index.php/archives/3223#more-3223"
}
],
"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"
}
]
}
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.