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.
13996 vulnerabilities reference this CWE, most recent first.
GHSA-8X29-769M-47CW
Vulnerability from github – Published: 2022-05-17 01:32 – Updated: 2022-05-17 01:32Directory traversal vulnerability in help.php in Trustport Webfilter 5.5.0.2232 allows remote attackers to read arbitrary files via a .. (dot dot) in the hf parameter.
{
"affected": [],
"aliases": [
"CVE-2013-5301"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2013-08-16T17:55:00Z",
"severity": "HIGH"
},
"details": "Directory traversal vulnerability in help.php in Trustport Webfilter 5.5.0.2232 allows remote attackers to read arbitrary files via a .. (dot dot) in the hf parameter.",
"id": "GHSA-8x29-769m-47cw",
"modified": "2022-05-17T01:32:35Z",
"published": "2022-05-17T01:32:35Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2013-5301"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/86289"
},
{
"type": "WEB",
"url": "http://archives.neohapsis.com/archives/bugtraq/2013-08/0043.html"
},
{
"type": "WEB",
"url": "http://packetstormsecurity.com/files/122735/Trustport-Webfilter-Traversal-File-Disclosure.html"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/61662"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-8X58-2QJG-XR22
Vulnerability from github – Published: 2023-12-07 06:30 – Updated: 2023-12-12 18:31An issue was discovered in server.js in etcd-browser 87ae63d75260. By supplying a /../../../ Directory Traversal input to the URL's GET request while connecting to the remote server port specified during setup, an attacker can retrieve local operating system files from the remote system.
{
"affected": [],
"aliases": [
"CVE-2023-46307"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-12-07T06:15:54Z",
"severity": "HIGH"
},
"details": "An issue was discovered in server.js in etcd-browser 87ae63d75260. By supplying a /../../../ Directory Traversal input to the URL\u0027s GET request while connecting to the remote server port specified during setup, an attacker can retrieve local operating system files from the remote system.",
"id": "GHSA-8x58-2qjg-xr22",
"modified": "2023-12-12T18:31:33Z",
"published": "2023-12-07T06:30:21Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-46307"
},
{
"type": "WEB",
"url": "https://hub.docker.com/r/buddho/etcd-browser"
},
{
"type": "WEB",
"url": "https://hub.docker.com/r/buddho/etcd-browser/tags"
},
{
"type": "WEB",
"url": "http://seclists.org/fulldisclosure/2023/Nov/11"
},
{
"type": "WEB",
"url": "http://seclists.org/fulldisclosure/2023/Nov/9"
}
],
"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-8X5Q-8C77-VQ49
Vulnerability from github – Published: 2023-01-16 18:30 – Updated: 2023-01-24 21:30A vulnerability has been found in frontaccounting faplanet and classified as critical. This vulnerability affects unknown code. The manipulation leads to path traversal. The name of the patch is a5dcd87f46080a624b1a9ad4b0dd035bbd24ac50. It is recommended to apply a patch to fix this issue. VDB-218398 is the identifier assigned to this vulnerability.
{
"affected": [],
"aliases": [
"CVE-2014-125080"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-01-16T18:15:00Z",
"severity": "CRITICAL"
},
"details": "A vulnerability has been found in frontaccounting faplanet and classified as critical. This vulnerability affects unknown code. The manipulation leads to path traversal. The name of the patch is a5dcd87f46080a624b1a9ad4b0dd035bbd24ac50. It is recommended to apply a patch to fix this issue. VDB-218398 is the identifier assigned to this vulnerability.",
"id": "GHSA-8x5q-8c77-vq49",
"modified": "2023-01-24T21:30:31Z",
"published": "2023-01-16T18:30:25Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2014-125080"
},
{
"type": "WEB",
"url": "https://github.com/frontaccounting/faplanet/commit/a5dcd87f46080a624b1a9ad4b0dd035bbd24ac50"
},
{
"type": "WEB",
"url": "https://vuldb.com/?ctiid.218398"
},
{
"type": "WEB",
"url": "https://vuldb.com/?id.218398"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-8X5V-8988-73V9
Vulnerability from github – Published: 2022-05-13 01:32 – Updated: 2022-05-13 01:32X-Pack Security versions 6.2.0, 6.2.1, and 6.2.2 are vulnerable to a user impersonation attack via incorrect XML canonicalization and DOM traversal. An attacker might have been able to impersonate a legitimate user if the SAML Identity Provider allows for self registration with arbitrary identifiers and the attacker can register an account which an identifier that shares a suffix with a legitimate account. Both of those conditions must be true in order to exploit this flaw.
{
"affected": [],
"aliases": [
"CVE-2018-3822"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2018-03-30T20:29:00Z",
"severity": "CRITICAL"
},
"details": "X-Pack Security versions 6.2.0, 6.2.1, and 6.2.2 are vulnerable to a user impersonation attack via incorrect XML canonicalization and DOM traversal. An attacker might have been able to impersonate a legitimate user if the SAML Identity Provider allows for self registration with arbitrary identifiers and the attacker can register an account which an identifier that shares a suffix with a legitimate account. Both of those conditions must be true in order to exploit this flaw.",
"id": "GHSA-8x5v-8988-73v9",
"modified": "2022-05-13T01:32:18Z",
"published": "2022-05-13T01:32:18Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2018-3822"
},
{
"type": "WEB",
"url": "https://discuss.elastic.co/t/elastic-stack-6-2-3-security-update/124848"
}
],
"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-8X66-X5GF-2PC8
Vulnerability from github – Published: 2025-06-23 21:31 – Updated: 2025-12-09 21:31RARLAB WinRAR Directory Traversal Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of RARLAB WinRAR. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.
The specific flaw exists within the handling of file paths within archive files. A crafted file path can cause the process to traverse to unintended directories. An attacker can leverage this vulnerability to execute code in the context of the current user. Was ZDI-CAN-27198.
{
"affected": [],
"aliases": [
"CVE-2025-6218"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-06-21T01:15:29Z",
"severity": "HIGH"
},
"details": "RARLAB WinRAR Directory Traversal Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of RARLAB WinRAR. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.\n\nThe specific flaw exists within the handling of file paths within archive files. A crafted file path can cause the process to traverse to unintended directories. An attacker can leverage this vulnerability to execute code in the context of the current user. Was ZDI-CAN-27198.",
"id": "GHSA-8x66-x5gf-2pc8",
"modified": "2025-12-09T21:31:29Z",
"published": "2025-06-23T21:31:49Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-6218"
},
{
"type": "WEB",
"url": "https://foresiet.com/blog/apt-c-08-winrar-directory-traversal-exploit"
},
{
"type": "WEB",
"url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-6218"
},
{
"type": "WEB",
"url": "https://www.secpod.com/blog/archive-terror-dissecting-the-winrar-cve-2025-6218-exploit-apt-c-08s-stealth-move"
},
{
"type": "WEB",
"url": "https://www.win-rar.com/singlenewsview.html?\u0026tx_ttnews%5Btt_news%5D=276\u0026cHash=388885bd3908a40726f535c026f94eb6"
},
{
"type": "WEB",
"url": "https://www.zerodayinitiative.com/advisories/ZDI-25-409"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-8X6F-M45X-3RJP
Vulnerability from github – Published: 2026-08-24 18:31 – Updated: 2026-08-25 15:32Multiple DrayTek VigorAP models contain a command injection vulnerability in the ExportSettings function. The vulnerability is caused by insufficient filtering of the backupkey, backuptype, and realtime fields before command execution. A remote attacker can trigger this vulnerability via crafted input to execute arbitrary commands with root privileges. Exploitation requires valid administrative credentials for the device's web management interface.
{
"affected": [],
"aliases": [
"CVE-2026-71905"
],
"database_specific": {
"cwe_ids": [
"CWE-22",
"CWE-78"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-24T18:17:01Z",
"severity": "HIGH"
},
"details": "Multiple DrayTek VigorAP models contain a command injection vulnerability in the ExportSettings function. The vulnerability is caused by insufficient filtering of the backupkey, backuptype, and realtime fields before command execution. A remote attacker can trigger this vulnerability via crafted input to execute arbitrary commands with root privileges. Exploitation requires valid administrative credentials for the device\u0027s web management interface.",
"id": "GHSA-8x6f-m45x-3rjp",
"modified": "2026-08-25T15:32:53Z",
"published": "2026-08-24T18:31:53Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-71905"
},
{
"type": "WEB",
"url": "https://github.com/Volmarg/personal-management-system/commit/a0443570e105ed4835ce57f3c0a3e33d5b77418c"
},
{
"type": "WEB",
"url": "https://github.com/Volmarg/personal-management-system/commit/fb9d3679d5b28977ef59e61c3eed42bec602ed8b"
},
{
"type": "WEB",
"url": "https://www.draytek.com/about/security-advisory/multiple-remote-code-execution-and-buffer-overflow-vulnerabilities-in-vigorap-series-august-2026"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/draytek-vigorap-multiple-models-os-command-injection-via-exportsettings"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/volmarg-personal-management-system-path-traversal-via-get-file-endpoint"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/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"
}
]
}
GHSA-8X9J-2P8R-7XC6
Vulnerability from github – Published: 2025-09-25 15:30 – Updated: 2025-09-25 16:54A vulnerability was identified in geyang ml-logger 0.10.36 and prior. Affected by this vulnerability is the function log_handler of the file ml_logger/server.py. Such manipulation of the argument File leads to path traversal. It is possible to launch the attack remotely. The exploit is publicly available and might be used. This product takes the approach of rolling releases to provide continious delivery. Therefore, version details for affected and updated releases are not available.
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "ml-logger"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"last_affected": "0.10.36"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2025-10951"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2025-09-25T16:53:59Z",
"nvd_published_at": "2025-09-25T15:16:10Z",
"severity": "MODERATE"
},
"details": "A vulnerability was identified in geyang ml-logger 0.10.36 and prior. Affected by this vulnerability is the function log_handler of the file ml_logger/server.py. Such manipulation of the argument File leads to path traversal. It is possible to launch the attack remotely. The exploit is publicly available and might be used. This product takes the approach of rolling releases to provide continious delivery. Therefore, version details for affected and updated releases are not available.",
"id": "GHSA-8x9j-2p8r-7xc6",
"modified": "2025-09-25T16:54:00Z",
"published": "2025-09-25T15:30:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-10951"
},
{
"type": "WEB",
"url": "https://github.com/geyang/ml-logger/issues/73"
},
{
"type": "PACKAGE",
"url": "https://github.com/geyang/ml-logger"
},
{
"type": "WEB",
"url": "https://vuldb.com/?ctiid.325821"
},
{
"type": "WEB",
"url": "https://vuldb.com/?id.325821"
},
{
"type": "WEB",
"url": "https://vuldb.com/?submit.652462"
}
],
"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"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P",
"type": "CVSS_V4"
}
],
"summary": "ml-logger has path traversal in the file argument"
}
GHSA-8X9J-6FV7-79G2
Vulnerability from github – Published: 2026-08-17 15:30 – Updated: 2026-08-17 15:30In Progress ShareFile Storage Zones Controller v5.12.5 and below, a party with valid zone credentials can perform path traversal using resumable upload initiation endpoint, allowing the party to write arbitrary content to any location writable by the application's service account. This may result in the execution of attacker-supplied code.
{
"affected": [],
"aliases": [
"CVE-2026-16137"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-17T14:20:19Z",
"severity": "HIGH"
},
"details": "In Progress ShareFile Storage Zones Controller v5.12.5 and below, a party with valid zone credentials can perform path traversal using resumable upload initiation endpoint, allowing the party to write arbitrary content to any location writable by the application\u0027s service account. This may result in the execution of attacker-supplied code.",
"id": "GHSA-8x9j-6fv7-79g2",
"modified": "2026-08-17T15:30:39Z",
"published": "2026-08-17T15:30:39Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-16137"
},
{
"type": "WEB",
"url": "https://support.sharefile.com/s/article/ShareFile-Storage-Zone-Controller-SZC-Service-Disruption-Guidance-Login-Issues-and-Access-Information"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-8X9R-HVWG-C55H
Vulnerability from github – Published: 2026-04-04 06:26 – Updated: 2026-04-07 14:21Zip Slip Path Traversal in coder/code-marketplace
Summary
A Zip Slip (CWE-22) vulnerability in coder/code-marketplace ≤ v2.4.1 allowed a malicious VSIX file to write arbitrary files outside the extension directory. ExtractZip passed raw zip entry names to a callback that wrote files via filepath.Join with no boundary check; filepath.Join resolved .. components but did not prevent the result from escaping the base path.
Root Cause
ExtractZip passed the raw, attacker-controlled zf.Name to a caller-supplied callback:
return false, fn(zf.Name, zr) // zf.Name not sanitized
AddExtension constructed the output path with filepath.Join and no boundary check:
path := filepath.Join(dir, name) // zip loop
path := filepath.Join(dir, file.RelativePath) // extra files loop
filepath.Clean resolved .. lexically but did not confine the result to dir:
filepath.Join("/srv/ext/pub/1.0", "../../../../etc/cron.d/evil")
→ "/etc/cron.d/evil"
Attack Scenario
An authenticated user (any upload-capable role) would submit a VSIX containing path-traversal entries.
On extraction, files would land at attacker-chosen paths writable by the marketplace process, enabling persistence (cron/init injection), SSH key injection, ld.so.preload hijacking, or binary overwrite depending on process privileges.
Fix
Addressed in https://github.com/coder/code-marketplace/releases/tag/v2.4.2
Recognition
Coder would like to thank Kandlaguduru Vamsi for responsibly disclosing this issue in accordance with https://coder.com/security/policy
{
"affected": [
{
"package": {
"ecosystem": "Go",
"name": "github.com/coder/code-marketplace"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.2.3-0.20260402184705-988440dee05f"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-35454"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2026-04-04T06:26:02Z",
"nvd_published_at": "2026-04-06T22:16:23Z",
"severity": "HIGH"
},
"details": "# Zip Slip Path Traversal in coder/code-marketplace\n\n## Summary\n\nA Zip Slip (CWE-22) vulnerability in `coder/code-marketplace` \u2264 v2.4.1 allowed a malicious VSIX file to write arbitrary files outside the extension directory. `ExtractZip` passed raw zip entry names to a callback that wrote files via `filepath.Join` with no boundary check; `filepath.Join` resolved `..` components but did not prevent the result from escaping the base path.\n\n\n## Root Cause\n\n`ExtractZip` passed the raw, attacker-controlled `zf.Name` to a caller-supplied callback:\n\n```go\nreturn false, fn(zf.Name, zr) // zf.Name not sanitized\n```\n\n`AddExtension` constructed the output path with `filepath.Join` and no boundary check:\n\n```go\npath := filepath.Join(dir, name) // zip loop\npath := filepath.Join(dir, file.RelativePath) // extra files loop\n```\n\n`filepath.Clean` resolved `..` lexically but did not confine the result to `dir`:\n\n```\nfilepath.Join(\"/srv/ext/pub/1.0\", \"../../../../etc/cron.d/evil\")\n \u2192 \"/etc/cron.d/evil\"\n```\n\n## Attack Scenario\n\nAn authenticated user (any upload-capable role) would submit a VSIX containing path-traversal entries.\n\nOn extraction, files would land at attacker-chosen paths writable by the marketplace process, enabling persistence (cron/init injection), SSH key injection, `ld.so.preload` hijacking, or binary overwrite depending on process privileges.\n\n## Fix\n\nAddressed in https://github.com/coder/code-marketplace/releases/tag/v2.4.2\n\n## Recognition\nCoder would like to thank [Kandlaguduru Vamsi](https://www.linkedin.com/in/vamsi-k-5419632a9/) for responsibly disclosing this issue in accordance with https://coder.com/security/policy",
"id": "GHSA-8x9r-hvwg-c55h",
"modified": "2026-04-07T14:21:34Z",
"published": "2026-04-04T06:26:02Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/coder/code-marketplace/security/advisories/GHSA-8x9r-hvwg-c55h"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-35454"
},
{
"type": "WEB",
"url": "https://github.com/coder/code-marketplace/commit/988440dee05fceef8400ed725badc604dbf90792"
},
{
"type": "PACKAGE",
"url": "https://github.com/coder/code-marketplace"
},
{
"type": "WEB",
"url": "https://github.com/coder/code-marketplace/releases/tag/v2.4.2"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Code Extension Marketplace: Zip Slip Path Traversal"
}
GHSA-8XF2-WHVM-VP6X
Vulnerability from github – Published: 2022-07-12 00:00 – Updated: 2022-07-17 00:00The seveas/golem repository through 2016-05-17 on GitHub allows absolute path traversal because the Flask send_file function is used unsafely.
{
"affected": [],
"aliases": [
"CVE-2022-31557"
],
"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 seveas/golem repository through 2016-05-17 on GitHub allows absolute path traversal because the Flask send_file function is used unsafely.",
"id": "GHSA-8xf2-whvm-vp6x",
"modified": "2022-07-17T00:00:44Z",
"published": "2022-07-12T00:00:58Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-31557"
},
{
"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"
}
]
}
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.