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.
13283 vulnerabilities reference this CWE, most recent first.
GHSA-HJC8-FQF6-6R5J
Vulnerability from github – Published: 2022-05-17 05:50 – Updated: 2022-05-17 05:50Directory traversal vulnerability in the BF Survey (com_bfsurvey) component for Joomla! allows remote attackers to include and execute arbitrary local files via a .. (dot dot) in the controller parameter to index.php.
{
"affected": [],
"aliases": [
"CVE-2010-2259"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2010-06-09T20:30:00Z",
"severity": "HIGH"
},
"details": "Directory traversal vulnerability in the BF Survey (com_bfsurvey) component for Joomla! allows remote attackers to include and execute arbitrary local files via a .. (dot dot) in the controller parameter to index.php.",
"id": "GHSA-hjc8-fqf6-6r5j",
"modified": "2022-05-17T05:50:36Z",
"published": "2022-05-17T05:50:36Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2010-2259"
},
{
"type": "WEB",
"url": "http://osvdb.org/61438"
},
{
"type": "WEB",
"url": "http://packetstormsecurity.org/1001-exploits/joomlabfsurvey-lfi.txt"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/37866"
},
{
"type": "WEB",
"url": "http://www.exploit-db.com/exploits/10946"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/37584"
},
{
"type": "WEB",
"url": "http://www.tamlyncreative.com.au/software/forum/index.php?topic=641.0"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-HJCH-CQPR-8PFQ
Vulnerability from github – Published: 2022-05-14 01:42 – Updated: 2022-05-14 01:42WeBid version up to current version 1.2.2 contains a Directory Traversal vulnerability in getthumb.php that can result in Arbitrary Image File Read. This attack appear to be exploitable via HTTP GET Request. This vulnerability appears to have been fixed in after commit 256a5f9d3eafbc477dcf77c7682446cc4b449c7f.
{
"affected": [],
"aliases": [
"CVE-2018-1000882"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2018-12-20T17:29:00Z",
"severity": "HIGH"
},
"details": "WeBid version up to current version 1.2.2 contains a Directory Traversal vulnerability in getthumb.php that can result in Arbitrary Image File Read. This attack appear to be exploitable via HTTP GET Request. This vulnerability appears to have been fixed in after commit 256a5f9d3eafbc477dcf77c7682446cc4b449c7f.",
"id": "GHSA-hjch-cqpr-8pfq",
"modified": "2022-05-14T01:42:48Z",
"published": "2022-05-14T01:42:48Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2018-1000882"
},
{
"type": "WEB",
"url": "https://github.com/renlok/WeBid/commit/256a5f9d3eafbc477dcf77c7682446cc4b449c7f"
},
{
"type": "WEB",
"url": "https://telekomsecurity.github.io/assets/advisories/20181108_WeBid_Multiple_Vulnerabilities.txt"
},
{
"type": "WEB",
"url": "http://bugs.webidsupport.com/view.php?id=646"
}
],
"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-HJF5-MQW9-9PH9
Vulnerability from github – Published: 2026-05-26 13:30 – Updated: 2026-05-26 13:30A security flaw has been discovered in NousResearch hermes-agent up to 2026.4.16. This vulnerability affects the function _is_blocked_device of the file tools/file_tools.py of the component read_file Tool. Performing a manipulation results in path traversal. The attack may be initiated remotely. The exploit has been released to the public and may be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.
{
"affected": [],
"aliases": [
"CVE-2026-9351"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-05-24T04:17:04Z",
"severity": "MODERATE"
},
"details": "A security flaw has been discovered in NousResearch hermes-agent up to 2026.4.16. This vulnerability affects the function _is_blocked_device of the file tools/file_tools.py of the component read_file Tool. Performing a manipulation results in path traversal. The attack may be initiated remotely. The exploit has been released to the public and may be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.",
"id": "GHSA-hjf5-mqw9-9ph9",
"modified": "2026-05-26T13:30:29Z",
"published": "2026-05-26T13:30:29Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-9351"
},
{
"type": "WEB",
"url": "https://gist.github.com/YLChen-007/1d1aeff404cb88e06ec2fb3377f49fef"
},
{
"type": "WEB",
"url": "https://vuldb.com/submit/812214"
},
{
"type": "WEB",
"url": "https://vuldb.com/vuln/365314"
},
{
"type": "WEB",
"url": "https://vuldb.com/vuln/365314/cti"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-HJH7-R5W8-5872
Vulnerability from github – Published: 2026-04-22 20:51 – Updated: 2026-04-27 16:34Summary
The fix for CVE-2026-30869 in SiYuan v3.5.10 only added a denylist check (IsSensitivePath) but did not address the root cause — a redundant url.PathUnescape() call in serveExport(). An authenticated attacker can use double URL encoding (%252e%252e) to traverse directories and read arbitrary workspace files including the full SQLite database (siyuan.db), kernel log, and all user documents.
Details
In kernel/server/serve.go, the serveExport() function (line 314-320) processes file paths as follows:
filePath := strings.TrimPrefix(c.Request.URL.Path, "/export/")
decodedPath, err := url.PathUnescape(filePath) // second decode
fullPath := filepath.Join(exportBaseDir, decodedPath)
Go's HTTP server already decodes percent-encoded characters once during request parsing. The additional url.PathUnescape() call creates a double-decode vulnerability:
- Attacker sends:
GET /export/%252e%252e/siyuan.db - Go HTTP decodes
%25→%, result:URL.Path = /export/%2e%2e/siyuan.db - Go's path cleaner sees
%2e%2eas literal characters (not..), no redirect occurs url.PathUnescape("%2e%2e")decodes to..filepath.Join(exportBaseDir, "../siyuan.db")resolves to<workspace>/temp/siyuan.db
The CVE-2026-30869 fix added IsSensitivePath() which blocks <workspace>/conf/ and OS-level paths (/etc, /root, etc.). However, it does NOT block:
- <workspace>/temp/siyuan.db — full document database
- <workspace>/temp/blocktree.db — block tree database
- <workspace>/temp/siyuan.log — kernel log
- <workspace>/temp/asset_content.db — asset content database
Note: the /appearance/ handler in the same file correctly uses gulu.File.IsSubPath() to validate paths (line 447), but this check is missing from the /export/ handler.
PoC
poc.zip Please extract the uploaded compressed file before proceeding
- docker compose up -d --build
- sh poc.sh
Impact
- Data exfiltration: An authenticated user (including low-privilege Publish/Reader users via the Publish service) can download the entire SQLite document database containing all blocks, documents, attributes, and full-text search indexes.
- Information disclosure: Kernel log (
siyuan.log) leaks internal server paths, versions, configuration details, and error messages.
{
"affected": [
{
"package": {
"ecosystem": "Go",
"name": "github.com/siyuan-note/siyuan/kernel"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.6.5"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-41894"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2026-04-22T20:51:22Z",
"nvd_published_at": "2026-04-24T19:17:14Z",
"severity": "HIGH"
},
"details": "### Summary\nThe fix for CVE-2026-30869 in SiYuan v3.5.10 only added a denylist check (`IsSensitivePath`) but did not address the root cause \u2014 a redundant `url.PathUnescape()` call in `serveExport()`. An authenticated attacker can use double URL encoding (`%252e%252e`) to traverse directories and read arbitrary workspace files including the full SQLite database (`siyuan.db`), kernel log, and all user documents.\n\n### Details\nIn `kernel/server/serve.go`, the `serveExport()` function (line 314-320) processes file paths as follows:\n\n```go\nfilePath := strings.TrimPrefix(c.Request.URL.Path, \"/export/\")\ndecodedPath, err := url.PathUnescape(filePath) // second decode\nfullPath := filepath.Join(exportBaseDir, decodedPath)\n```\n\nGo\u0027s HTTP server already decodes percent-encoded characters once during request parsing. The additional `url.PathUnescape()` call creates a double-decode vulnerability:\n\n1. Attacker sends: `GET /export/%252e%252e/siyuan.db`\n2. Go HTTP decodes `%25` \u2192 `%`, result: `URL.Path = /export/%2e%2e/siyuan.db`\n3. Go\u0027s path cleaner sees `%2e%2e` as literal characters (not `..`), no redirect occurs\n4. `url.PathUnescape(\"%2e%2e\")` decodes to `..`\n5. `filepath.Join(exportBaseDir, \"../siyuan.db\")` resolves to `\u003cworkspace\u003e/temp/siyuan.db`\n\nThe CVE-2026-30869 fix added `IsSensitivePath()` which blocks `\u003cworkspace\u003e/conf/` and OS-level paths (`/etc`, `/root`, etc.). However, it does NOT block:\n- `\u003cworkspace\u003e/temp/siyuan.db` \u2014 full document database\n- `\u003cworkspace\u003e/temp/blocktree.db` \u2014 block tree database\n- `\u003cworkspace\u003e/temp/siyuan.log` \u2014 kernel log\n- `\u003cworkspace\u003e/temp/asset_content.db` \u2014 asset content database\n\nNote: the `/appearance/` handler in the same file correctly uses `gulu.File.IsSubPath()` to validate paths (line 447), but this check is missing from the `/export/` handler.\n\n### PoC\n[poc.zip](https://github.com/user-attachments/files/26866234/poc.zip)\nPlease extract the uploaded compressed file before proceeding\n\n1. docker compose up -d --build\n2. sh poc.sh\n\n\u003cimg width=\"550\" height=\"184\" alt=\"\u1109\u1173\u110f\u1173\u1105\u1175\u11ab\u1109\u1163\u11ba 2026-04-19 \u110b\u1169\u1112\u116e 5 08 30\" src=\"https://github.com/user-attachments/assets/6aea4334-0b5a-4f45-bd1f-ecfad61ba524\" /\u003e\n\n\n\n\n### Impact\n- Data exfiltration: An authenticated user (including low-privilege Publish/Reader users via the Publish service) can download the entire SQLite document database containing all blocks, documents, attributes, and full-text search indexes.\n- Information disclosure: Kernel log (`siyuan.log`) leaks internal server paths, versions, configuration details, and error messages.",
"id": "GHSA-hjh7-r5w8-5872",
"modified": "2026-04-27T16:34:02Z",
"published": "2026-04-22T20:51:22Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-hjh7-r5w8-5872"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-41894"
},
{
"type": "WEB",
"url": "https://github.com/siyuan-note/siyuan/commit/bb481e1290c4a34255652ede85a546504505d2a7"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-2h2p-mvfx-868w"
},
{
"type": "PACKAGE",
"url": "https://github.com/siyuan-note/siyuan"
},
{
"type": "WEB",
"url": "https://github.com/siyuan-note/siyuan/releases/tag/v3.6.5"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "SiYuan: Path Traversal via Double URL Encoding in `/export/` Endpoint (Incomplete Fix Bypass for CVE-2026-30869)"
}
GHSA-HJHX-FHJ9-6G3J
Vulnerability from github – Published: 2022-05-24 19:12 – Updated: 2022-05-24 19:12In NASCENT RemKon Device Manager 4.0.0.0, a Directory Traversal vulnerability in a log-reading function in maintenance/readLog.php allows an attacker to read any file via a specialized URL.
{
"affected": [],
"aliases": [
"CVE-2021-38612"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2021-08-24T12:15:00Z",
"severity": "HIGH"
},
"details": "In NASCENT RemKon Device Manager 4.0.0.0, a Directory Traversal vulnerability in a log-reading function in maintenance/readLog.php allows an attacker to read any file via a specialized URL.",
"id": "GHSA-hjhx-fhj9-6g3j",
"modified": "2022-05-24T19:12:05Z",
"published": "2022-05-24T19:12:05Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-38612"
},
{
"type": "WEB",
"url": "https://www.blacklanternsecurity.com/2021-08-23-Nascent-RemKon-CVEs"
},
{
"type": "WEB",
"url": "https://www.nascent.com/single-post/2019/01/17/nascent-technology-releases-remkon-31-to-enhance-audio-experience"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-HJJ2-QQ3C-3555
Vulnerability from github – Published: 2022-05-13 01:22 – Updated: 2022-05-13 01:22An issue was discovered in PHPMyWind 5.5. It allows remote attackers to delete arbitrary folders via an admin/database_backup.php?action=import&dopost=deldir&tbname=../ URI.
{
"affected": [],
"aliases": [
"CVE-2019-7403"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2019-02-05T16:29:00Z",
"severity": "MODERATE"
},
"details": "An issue was discovered in PHPMyWind 5.5. It allows remote attackers to delete arbitrary folders via an admin/database_backup.php?action=import\u0026dopost=deldir\u0026tbname=../ URI.",
"id": "GHSA-hjj2-qq3c-3555",
"modified": "2022-05-13T01:22:50Z",
"published": "2022-05-13T01:22:50Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2019-7403"
},
{
"type": "WEB",
"url": "https://github.com/panghusec/exploit/issues/9"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-HJJ3-76X6-4W3X
Vulnerability from github – Published: 2024-11-22 21:32 – Updated: 2025-09-23 12:31A path traversal vulnerability has been reported to affect several QNAP operating system versions. If exploited, the vulnerability could allow remote attackers who have gained administrator access to read the contents of unexpected files and expose sensitive data.
We have already fixed the vulnerability in the following versions: QTS 5.2.1.2930 build 20241025 and later QuTS hero h5.2.1.2929 build 20241025 and later
{
"affected": [],
"aliases": [
"CVE-2024-37043"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-11-22T16:15:23Z",
"severity": "MODERATE"
},
"details": "A path traversal vulnerability has been reported to affect several QNAP operating system versions. If exploited, the vulnerability could allow remote attackers who have gained administrator access to read the contents of unexpected files and expose sensitive data.\n\nWe have already fixed the vulnerability in the following versions:\nQTS 5.2.1.2930 build 20241025 and later\nQuTS hero h5.2.1.2929 build 20241025 and later",
"id": "GHSA-hjj3-76x6-4w3x",
"modified": "2025-09-23T12:31:11Z",
"published": "2024-11-22T21:32:14Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-37043"
},
{
"type": "WEB",
"url": "https://www.qnap.com/en/security-advisory/qsa-24-43"
}
],
"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"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-HJJ4-CH7M-P53M
Vulnerability from github – Published: 2022-05-24 17:21 – Updated: 2022-05-24 17:21An issue was discovered in Mattermost Mobile Apps before 1.26.0. An attacker can use directory traversal with the Video Preview feature to overwrite arbitrary files on a device.
{
"affected": [],
"aliases": [
"CVE-2019-20851"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2020-06-19T15:15:00Z",
"severity": "MODERATE"
},
"details": "An issue was discovered in Mattermost Mobile Apps before 1.26.0. An attacker can use directory traversal with the Video Preview feature to overwrite arbitrary files on a device.",
"id": "GHSA-hjj4-ch7m-p53m",
"modified": "2022-05-24T17:21:11Z",
"published": "2022-05-24T17:21:11Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2019-20851"
},
{
"type": "WEB",
"url": "https://mattermost.com/security-updates"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-HJJH-VQWX-HV5W
Vulnerability from github – Published: 2022-05-17 01:39 – Updated: 2022-05-17 01:39Directory traversal vulnerability in Tiny Server 1.1.5 allows remote authenticated users to read arbitrary files via a .. (dot dot) in the URI of an HTTP request.
{
"affected": [],
"aliases": [
"CVE-2012-5335"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2012-10-08T23:55:00Z",
"severity": "MODERATE"
},
"details": "Directory traversal vulnerability in Tiny Server 1.1.5 allows remote authenticated users to read arbitrary files via a .. (dot dot) in the URI of an HTTP request.",
"id": "GHSA-hjjh-vqwx-hv5w",
"modified": "2022-05-17T01:39:48Z",
"published": "2022-05-17T01:39:48Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2012-5335"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/74114"
},
{
"type": "WEB",
"url": "http://www.exploit-db.com/exploits/18610"
},
{
"type": "WEB",
"url": "http://www.osvdb.org/80586"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/52541"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-HJJM-R972-JJW7
Vulnerability from github – Published: 2022-05-02 03:35 – Updated: 2022-05-02 03:35Directory traversal vulnerability in maillinglist/admin/change_config.php in ADbNewsSender before 1.5.6 allows remote attackers to include and execute arbitrary local files via a .. (dot dot) in the path_to_lang parameter.
{
"affected": [],
"aliases": [
"CVE-2009-2449"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2009-07-13T17:30:00Z",
"severity": "HIGH"
},
"details": "Directory traversal vulnerability in maillinglist/admin/change_config.php in ADbNewsSender before 1.5.6 allows remote attackers to include and execute arbitrary local files via a .. (dot dot) in the path_to_lang parameter.",
"id": "GHSA-hjjm-r972-jjw7",
"modified": "2022-05-02T03:35:19Z",
"published": "2022-05-02T03:35:19Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2009-2449"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/35845"
},
{
"type": "WEB",
"url": "http://sourceforge.net/apps/mantisbt/adbnewssender/view.php?id=22"
},
{
"type": "WEB",
"url": "http://sourceforge.net/project/shownotes.php?release_id=694644"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/35596"
}
],
"schema_version": "1.4.0",
"severity": []
}
Mitigation MIT-5.1
Strategy: Input Validation
- Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
- When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434.
- Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would be removed from the original string, but the remaining characters would still form the "../" string.
Mitigation MIT-15
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Mitigation MIT-20.1
Strategy: Input Validation
- Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
- Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59). This includes:
- realpath() in C
- getCanonicalPath() in Java
- GetFullPath() in ASP.NET
- realpath() or abs_path() in Perl
- realpath() in PHP
Mitigation MIT-4
Strategy: Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
Mitigation MIT-29
Strategy: Firewall
Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].
Mitigation MIT-17
Strategy: Environment Hardening
Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
Mitigation MIT-21.1
Strategy: Enforcement by Conversion
- When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
- For example, ID 1 could map to "inbox.txt" and ID 2 could map to "profile.txt". Features such as the ESAPI AccessReferenceMap [REF-185] provide this capability.
Mitigation MIT-22
Strategy: Sandbox or Jail
- Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.
- OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations.
- This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise.
- Be careful to avoid CWE-243 and other weaknesses related to jails.
Mitigation MIT-34
Strategy: Attack Surface Reduction
- Store library, include, and utility files outside of the web document root, if possible. Otherwise, store them in a separate directory and use the web server's access control capabilities to prevent attackers from directly requesting them. One common practice is to define a fixed constant in each calling program, then check for the existence of the constant in the library/include file; if the constant does not exist, then the file was directly requested, and it can exit immediately.
- This significantly reduces the chance of an attacker being able to bypass any protection mechanisms that are in the base program but not in the include files. It will also reduce the attack surface.
Mitigation MIT-39
- Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success.
- If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files.
- Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not.
- In the context of path traversal, error messages which disclose path information can help attackers craft the appropriate attack strings to move through the file system hierarchy.
Mitigation MIT-16
Strategy: Environment Hardening
When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
CAPEC-126: Path Traversal
An adversary uses path manipulation methods to exploit insufficient input validation of a target to obtain access to data that should be not be retrievable by ordinary well-formed requests. A typical variety of this attack involves specifying a path to a desired file together with dot-dot-slash characters, resulting in the file access API or function traversing out of the intended directory structure and into the root file system. By replacing or modifying the expected path information the access function or API retrieves the file desired by the attacker. These attacks either involve the attacker providing a complete path to a targeted file or using control characters (e.g. path separators (/ or \) and/or dots (.)) to reach desired directories or files.
CAPEC-64: Using Slashes and URL Encoding Combined to Bypass Validation Logic
This attack targets the encoding of the URL combined with the encoding of the slash characters. An attacker can take advantage of the multiple ways of encoding a URL and abuse the interpretation of the URL. A URL may contain special character that need special syntax handling in order to be interpreted. Special characters are represented using a percentage character followed by two digits representing the octet code of the original character (%HEX-CODE). For instance US-ASCII space character would be represented with %20. This is often referred as escaped ending or percent-encoding. Since the server decodes the URL from the requests, it may restrict the access to some URL paths by validating and filtering out the URL requests it received. An attacker will try to craft an URL with a sequence of special characters which once interpreted by the server will be equivalent to a forbidden URL. It can be difficult to protect against this attack since the URL can contain other format of encoding such as UTF-8 encoding, Unicode-encoding, etc.
CAPEC-76: Manipulating Web Input to File System Calls
An attacker manipulates inputs to the target software which the target software passes to file system calls in the OS. The goal is to gain access to, and perhaps modify, areas of the file system that the target software did not intend to be accessible.
CAPEC-78: Using Escaped Slashes in Alternate Encoding
This attack targets the use of the backslash in alternate encoding. An adversary can provide a backslash as a leading character and causes a parser to believe that the next character is special. This is called an escape. By using that trick, the adversary tries to exploit alternate ways to encode the same character which leads to filter problems and opens avenues to attack.
CAPEC-79: Using Slashes in Alternate Encoding
This attack targets the encoding of the Slash characters. An adversary would try to exploit common filtering problems related to the use of the slashes characters to gain access to resources on the target host. Directory-driven systems, such as file systems and databases, typically use the slash character to indicate traversal between directories or other container components. For murky historical reasons, PCs (and, as a result, Microsoft OSs) choose to use a backslash, whereas the UNIX world typically makes use of the forward slash. The schizophrenic result is that many MS-based systems are required to understand both forms of the slash. This gives the adversary many opportunities to discover and abuse a number of common filtering problems. The goal of this pattern is to discover server software that only applies filters to one version, but not the other.