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.
13575 vulnerabilities reference this CWE, most recent first.
GHSA-HM2R-JQ47-7576
Vulnerability from github – Published: 2023-04-11 18:30 – Updated: 2024-04-04 03:24A relative path traversal vulnerability in Fortinet FortiClient (Windows) 7.0.0 - 7.0.7, 6.4.0 - 6.4.9, 6.2.0 - 6.2.9 and 6.0.0 - 6.0.10 allows an attacker to execute unauthorized code or commands via sending a crafted request to a specific named pipe.
{
"affected": [],
"aliases": [
"CVE-2022-42470"
],
"database_specific": {
"cwe_ids": [
"CWE-22",
"CWE-23"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-04-11T17:15:00Z",
"severity": "HIGH"
},
"details": "A relative path traversal vulnerability in Fortinet FortiClient (Windows) 7.0.0 - 7.0.7, 6.4.0 - 6.4.9, 6.2.0 - 6.2.9 and 6.0.0 - 6.0.10 allows an attacker to execute unauthorized code or commands via sending a crafted request to a specific named pipe.",
"id": "GHSA-hm2r-jq47-7576",
"modified": "2024-04-04T03:24:29Z",
"published": "2023-04-11T18:30:29Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-42470"
},
{
"type": "WEB",
"url": "https://fortiguard.com/psirt/FG-IR-22-320"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-HM36-8847-6HHF
Vulnerability from github – Published: 2022-05-24 17:03 – Updated: 2023-02-02 21:34A vulnerability has been identified in EN100 Ethernet module DNP3 variant (All versions), EN100 Ethernet module IEC 61850 variant (All versions < V4.37), EN100 Ethernet module IEC104 variant (All versions), EN100 Ethernet module Modbus TCP variant (All versions), EN100 Ethernet module PROFINET IO variant (All versions). A vulnerability in the integrated web server of the affected devices could allow unauthorized attackers to obtain sensitive information about the device, including logs and configurations. At the time of advisory publication no public exploitation of this security vulnerability was known.
{
"affected": [],
"aliases": [
"CVE-2019-13944"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2019-12-12T19:15:00Z",
"severity": "MODERATE"
},
"details": "A vulnerability has been identified in EN100 Ethernet module DNP3 variant (All versions), EN100 Ethernet module IEC 61850 variant (All versions \u003c V4.37), EN100 Ethernet module IEC104 variant (All versions), EN100 Ethernet module Modbus TCP variant (All versions), EN100 Ethernet module PROFINET IO variant (All versions). A vulnerability in the integrated web server of the affected devices could allow unauthorized attackers to obtain sensitive information about the device, including logs and configurations. At the time of advisory publication no public exploitation of this security vulnerability was known.",
"id": "GHSA-hm36-8847-6hhf",
"modified": "2023-02-02T21:34:22Z",
"published": "2022-05-24T17:03:20Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2019-13944"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/pdf/ssa-418979.pdf"
},
{
"type": "WEB",
"url": "https://www.us-cert.gov/ics/advisories/icsa-19-344-07"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-HM39-3528-68F4
Vulnerability from github – Published: 2022-05-14 00:58 – Updated: 2022-05-14 00:58An issue was discovered in BlogEngine.NET through 3.3.6.0. A path traversal and Local File Inclusion vulnerability in PostList.ascx.cs can cause unauthenticated users to load a PostView.ascx component from a potentially untrusted location on the local filesystem. This is especially dangerous if an authenticated user uploads a PostView.ascx file using the file manager utility, which is currently allowed. This results in remote code execution for an authenticated user.
{
"affected": [],
"aliases": [
"CVE-2019-6714"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2019-03-21T16:01:00Z",
"severity": "CRITICAL"
},
"details": "An issue was discovered in BlogEngine.NET through 3.3.6.0. A path traversal and Local File Inclusion vulnerability in PostList.ascx.cs can cause unauthenticated users to load a PostView.ascx component from a potentially untrusted location on the local filesystem. This is especially dangerous if an authenticated user uploads a PostView.ascx file using the file manager utility, which is currently allowed. This results in remote code execution for an authenticated user.",
"id": "GHSA-hm39-3528-68f4",
"modified": "2022-05-14T00:58:06Z",
"published": "2022-05-14T00:58:06Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2019-6714"
},
{
"type": "WEB",
"url": "https://blogengine.io"
},
{
"type": "WEB",
"url": "https://github.com/rxtur/BlogEngine.NET"
},
{
"type": "WEB",
"url": "https://www.exploit-db.com/exploits/46353"
},
{
"type": "WEB",
"url": "http://packetstormsecurity.com/files/151628/BlogEngine.NET-3.3.6-Directory-Traversal-Remote-Code-Execution.html"
},
{
"type": "WEB",
"url": "http://seclists.org/fulldisclosure/2019/Jun/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-HM3F-Q6RW-M6WH
Vulnerability from github – Published: 2026-03-09 17:41 – Updated: 2026-03-09 17:41Impact
The PagesRouter static file serving route is vulnerable to a path traversal attack that allows unauthenticated reading of files outside the configured pagesPath directory. The boundary check uses a string prefix comparison without enforcing a directory separator boundary. An attacker can use path traversal sequences to access files in sibling directories whose names share the same prefix as the pages directory (e.g. pages-secret starts with pages).
This affects any Parse Server deployment with the pages feature enabled (pages.enableRouter: true). Exploitation requires a sibling directory of pagesPath whose name begins with the same string as the pages directory name.
Patches
The fix enforces a path separator boundary in the check, ensuring resolved paths must be strictly inside the pagesPath directory.
Workarounds
Ensure the pagesPath directory has no sibling directories whose names begin with the same prefix. For example, if pagesPath is /srv/pages, ensure no directory like /srv/pages-backup or /srv/pages_old exists alongside it.
References
- GitHub security advisory: https://github.com/parse-community/parse-server/security/advisories/GHSA-hm3f-q6rw-m6wh
- Fix for Parse Server 9: https://github.com/parse-community/parse-server/releases/tag/9.5.0-alpha.8
- Fix for Parse Server 8: https://github.com/parse-community/parse-server/releases/tag/8.6.8
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "parse-server"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "8.6.8"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "npm",
"name": "parse-server"
},
"ranges": [
{
"events": [
{
"introduced": "9.0.0-alpha.1"
},
{
"fixed": "9.5.0-alpha.8"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-30848"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2026-03-09T17:41:55Z",
"nvd_published_at": "2026-03-07T17:15:52Z",
"severity": "MODERATE"
},
"details": "### Impact\n\nThe `PagesRouter` static file serving route is vulnerable to a path traversal attack that allows unauthenticated reading of files outside the configured `pagesPath` directory. The boundary check uses a string prefix comparison without enforcing a directory separator boundary. An attacker can use path traversal sequences to access files in sibling directories whose names share the same prefix as the pages directory (e.g. `pages-secret` starts with `pages`).\n\nThis affects any Parse Server deployment with the `pages` feature enabled (`pages.enableRouter: true`). Exploitation requires a sibling directory of `pagesPath` whose name begins with the same string as the pages directory name.\n\n### Patches\n\nThe fix enforces a path separator boundary in the check, ensuring resolved paths must be strictly inside the `pagesPath` directory.\n\n### Workarounds\n\nEnsure the `pagesPath` directory has no sibling directories whose names begin with the same prefix. For example, if `pagesPath` is `/srv/pages`, ensure no directory like `/srv/pages-backup` or `/srv/pages_old` exists alongside it.\n\n### References\n\n- GitHub security advisory: https://github.com/parse-community/parse-server/security/advisories/GHSA-hm3f-q6rw-m6wh\n- Fix for Parse Server 9: https://github.com/parse-community/parse-server/releases/tag/9.5.0-alpha.8\n- Fix for Parse Server 8: https://github.com/parse-community/parse-server/releases/tag/8.6.8",
"id": "GHSA-hm3f-q6rw-m6wh",
"modified": "2026-03-09T17:41:55Z",
"published": "2026-03-09T17:41:55Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/parse-community/parse-server/security/advisories/GHSA-hm3f-q6rw-m6wh"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-30848"
},
{
"type": "PACKAGE",
"url": "https://github.com/parse-community/parse-server"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Parse Server: `PagesRouter` path traversal allows reading files outside configured pages directory"
}
GHSA-HM3M-339Q-Q9MH
Vulnerability from github – Published: 2022-05-14 01:50 – Updated: 2022-05-14 01:50An issue was discovered in LAOBANCMS 2.0. It allows arbitrary file deletion via ../ directory traversal in the admin/pic.php del parameter, as demonstrated by deleting install/install.txt to permit a reinstallation.
{
"affected": [],
"aliases": [
"CVE-2018-19228"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2018-11-12T20:29:00Z",
"severity": "HIGH"
},
"details": "An issue was discovered in LAOBANCMS 2.0. It allows arbitrary file deletion via ../ directory traversal in the admin/pic.php del parameter, as demonstrated by deleting install/install.txt to permit a reinstallation.",
"id": "GHSA-hm3m-339q-q9mh",
"modified": "2022-05-14T01:50:16Z",
"published": "2022-05-14T01:50:16Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2018-19228"
},
{
"type": "WEB",
"url": "https://github.com/AvaterXXX/laobanCMS/blob/master/1.md#del-file"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-HM5P-82G6-M3XH
Vulnerability from github – Published: 2026-01-30 14:43 – Updated: 2026-01-30 14:43Impact
It's possible for an authenticated backoffice-user to enumerate and traverse paths/files on the systems filesystem and read their contents, on Mac/Linux Umbraco installations using Forms. As Umbraco Cloud runs in a Windows environment, Cloud users aren't affected.
Patches
This issue affects versions 16 and 17 of Umbraco Forms and is patched in 16.4.1 and 17.1.1
Workarounds
If upgrading is not immediately possible, users can mitigate this vulnerability by:
* Configuring a WAF or reverse proxy to block requests containing path traversal sequences (../, ..\) in the fileName parameter of the export endpoint
* Restricting network access to the Umbraco backoffice to trusted IP ranges
* Blocking the /umbraco/forms/api/v1/export endpoint entirely if the export feature is not required
However, upgrading to the patched version is strongly recommended.
References
Credit to Kevin Joensen from Baldur Security for finding this vulnerability
{
"affected": [
{
"package": {
"ecosystem": "NuGet",
"name": "Umbraco.Forms"
},
"ranges": [
{
"events": [
{
"introduced": "16.0.0"
},
{
"fixed": "16.4.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "NuGet",
"name": "Umbraco.Forms"
},
"ranges": [
{
"events": [
{
"introduced": "17.0.0"
},
{
"fixed": "17.1.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-24687"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2026-01-30T14:43:18Z",
"nvd_published_at": "2026-01-29T20:16:10Z",
"severity": "MODERATE"
},
"details": "### Impact\nIt\u0027s possible for an authenticated backoffice-user to enumerate and traverse paths/files on the systems filesystem and read their contents, on Mac/Linux Umbraco installations using Forms. As Umbraco Cloud runs in a Windows environment, Cloud users aren\u0027t affected. \n\n### Patches\nThis issue affects versions 16 and 17 of Umbraco Forms and is patched in 16.4.1 and 17.1.1\n\n### Workarounds\nIf upgrading is not immediately possible, users can mitigate this vulnerability by:\n* Configuring a WAF or reverse proxy to block requests containing path traversal sequences (`../`, `..\\`) in the `fileName` parameter of the export endpoint\n* Restricting network access to the Umbraco backoffice to trusted IP ranges\n* Blocking the `/umbraco/forms/api/v1/export` endpoint entirely if the export feature is not required\n\nHowever, upgrading to the patched version is strongly recommended.\n\n### References\nCredit to Kevin Joensen from Baldur Security for finding this vulnerability",
"id": "GHSA-hm5p-82g6-m3xh",
"modified": "2026-01-30T14:43:18Z",
"published": "2026-01-30T14:43:18Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/umbraco/Umbraco.Forms.Issues/security/advisories/GHSA-hm5p-82g6-m3xh"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-24687"
},
{
"type": "PACKAGE",
"url": "https://github.com/umbraco/Umbraco.Forms.Issues"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Umbraco.Forms has Path Traversal and File Enumeration Vulnerabilities in Linux/Mac"
}
GHSA-HM7J-M87F-5473
Vulnerability from github – Published: 2022-06-25 00:00 – Updated: 2022-07-07 00:00Dell WMS 3.6.1 and below contains a Path Traversal vulnerability in Device API. A remote attacker could potentially exploit this vulnerability, to gain unauthorized read access to the files stored on the server filesystem, with the privileges of the running web application.
{
"affected": [],
"aliases": [
"CVE-2022-29097"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-06-24T17:15:00Z",
"severity": "MODERATE"
},
"details": "Dell WMS 3.6.1 and below contains a Path Traversal vulnerability in Device API. A remote attacker could potentially exploit this vulnerability, to gain unauthorized read access to the files stored on the server filesystem, with the privileges of the running web application.",
"id": "GHSA-hm7j-m87f-5473",
"modified": "2022-07-07T00:00:26Z",
"published": "2022-06-25T00:00:52Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-29097"
},
{
"type": "WEB",
"url": "https://www.dell.com/support/kbdoc/en-us/000200215/dsa-2022-143-dell-wyse-management-suite-security-update-for-multiple-vulnerabilities"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-HM8J-79H4-Q2C7
Vulnerability from github – Published: 2022-05-14 02:49 – Updated: 2025-04-12 12:44Directory traversal vulnerability in pixabay-images.php in the Pixabay Images plugin before 2.4 for WordPress allows remote attackers to write to arbitrary files via a .. (dot dot) in the q parameter.
{
"affected": [],
"aliases": [
"CVE-2015-1365"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2015-01-27T20:04:00Z",
"severity": "MODERATE"
},
"details": "Directory traversal vulnerability in pixabay-images.php in the Pixabay Images plugin before 2.4 for WordPress allows remote attackers to write to arbitrary files via a .. (dot dot) in the q parameter.",
"id": "GHSA-hm8j-79h4-q2c7",
"modified": "2025-04-12T12:44:43Z",
"published": "2022-05-14T02:49:50Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2015-1365"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/100036"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/changeset?sfp_email=\u0026sfph_mail=\u0026reponame=\u0026new=1067992%40pixabay-images%2Ftrunk%2Fpixabay-images.php\u0026old=926633%40pixabay-images%2Ftrunk%2Fpixabay-images.php"
},
{
"type": "WEB",
"url": "https://wordpress.org/plugins/pixabay-images/changelog"
},
{
"type": "WEB",
"url": "https://www.mogwaisecurity.de/advisories/MSA-2015-01.txt"
},
{
"type": "WEB",
"url": "http://osvdb.org/show/osvdb/117147"
},
{
"type": "WEB",
"url": "http://packetstormsecurity.com/files/130017/WordPress-Pixarbay-Images-2.3-XSS-Bypass-Upload-Traversal.html"
},
{
"type": "WEB",
"url": "http://seclists.org/fulldisclosure/2015/Jan/75"
},
{
"type": "WEB",
"url": "http://www.exploit-db.com/exploits/35846"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2015/01/25/5"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/archive/1/534505/100/0/threaded"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-HM95-XQG2-4W57
Vulnerability from github – Published: 2024-04-10 18:30 – Updated: 2024-04-10 18:30qdrant/qdrant is vulnerable to a path traversal and arbitrary file upload vulnerability via the /collections/{COLLECTION}/snapshots/upload endpoint, specifically through the snapshot parameter. This vulnerability allows attackers to upload and overwrite any file on the filesystem, leading to potential remote code execution. This issue affects the integrity and availability of the system, enabling unauthorized access and potentially causing the server to malfunction.
{
"affected": [],
"aliases": [
"CVE-2024-2221"
],
"database_specific": {
"cwe_ids": [
"CWE-22",
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-04-10T17:15:54Z",
"severity": "CRITICAL"
},
"details": "qdrant/qdrant is vulnerable to a path traversal and arbitrary file upload vulnerability via the `/collections/{COLLECTION}/snapshots/upload` endpoint, specifically through the `snapshot` parameter. This vulnerability allows attackers to upload and overwrite any file on the filesystem, leading to potential remote code execution. This issue affects the integrity and availability of the system, enabling unauthorized access and potentially causing the server to malfunction.",
"id": "GHSA-hm95-xqg2-4w57",
"modified": "2024-04-10T18:30:48Z",
"published": "2024-04-10T18:30:48Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-2221"
},
{
"type": "WEB",
"url": "https://github.com/qdrant/qdrant/commit/e6411907f0ecf3c2f8ba44ab704b9e4597d9705d"
},
{
"type": "WEB",
"url": "https://huntr.com/bounties/6be8d4e3-67e6-4660-a8db-04215a1cff3e"
}
],
"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-HM9H-WF2R-4PC5
Vulnerability from github – Published: 2022-05-24 17:12 – Updated: 2022-10-07 18:16A CWE-22: Improper Limitation of a Pathname to a Restricted Directory exists in IGSS (Versions 14 and prior using the service: IGSSupdate), which could allow a remote unauthenticated attacker to read arbitrary files from the IGSS server PC on an unrestricted or shared network when the IGSS Update Service is enabled.
{
"affected": [],
"aliases": [
"CVE-2020-7478"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2020-03-23T20:15:00Z",
"severity": "MODERATE"
},
"details": "A CWE-22: Improper Limitation of a Pathname to a Restricted Directory exists in IGSS (Versions 14 and prior using the service: IGSSupdate), which could allow a remote unauthenticated attacker to read arbitrary files from the IGSS server PC on an unrestricted or shared network when the IGSS Update Service is enabled.",
"id": "GHSA-hm9h-wf2r-4pc5",
"modified": "2022-10-07T18:16:04Z",
"published": "2022-05-24T17:12:16Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2020-7478"
},
{
"type": "WEB",
"url": "https://www.se.com/ww/en/download/document/SEVD-2020-070-01"
},
{
"type": "WEB",
"url": "https://www.zerodayinitiative.com/advisories/ZDI-20-371"
}
],
"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"
}
]
}
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.