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.
13217 vulnerabilities reference this CWE, most recent first.
GHSA-GHQH-HJHP-P556
Vulnerability from github – Published: 2022-05-24 19:06 – Updated: 2022-05-24 19:06Adobe RoboHelp Server version 2019.0.9 (and earlier) is affected by a Path Traversal vulnerability when parsing a crafted HTTP POST request. An authenticated attacker could leverage this vulnerability to achieve arbitrary code execution in the context of the current user. Exploitation of this issue does not require user interaction.
{
"affected": [],
"aliases": [
"CVE-2021-28588"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2021-06-28T15:15:00Z",
"severity": "HIGH"
},
"details": "Adobe RoboHelp Server version 2019.0.9 (and earlier) is affected by a Path Traversal vulnerability when parsing a crafted HTTP POST request. An authenticated attacker could leverage this vulnerability to achieve arbitrary code execution in the context of the current user. Exploitation of this issue does not require user interaction.",
"id": "GHSA-ghqh-hjhp-p556",
"modified": "2022-05-24T19:06:24Z",
"published": "2022-05-24T19:06:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-28588"
},
{
"type": "WEB",
"url": "https://www.zerodayinitiative.com/advisories/ZDI-21-660"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-GHQQ-JFX7-F6M9
Vulnerability from github – Published: 2023-06-09 03:30 – Updated: 2023-06-14 19:26Path Traversal in GitHub repository froxlor/froxlor prior to 2.0.20.
{
"affected": [
{
"package": {
"ecosystem": "Packagist",
"name": "froxlor/froxlor"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.0.20"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2023-3172"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2023-06-09T22:41:31Z",
"nvd_published_at": "2023-06-09T01:15:30Z",
"severity": "HIGH"
},
"details": "Path Traversal in GitHub repository froxlor/froxlor prior to 2.0.20.",
"id": "GHSA-ghqq-jfx7-f6m9",
"modified": "2023-06-14T19:26:52Z",
"published": "2023-06-09T03:30:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-3172"
},
{
"type": "WEB",
"url": "https://github.com/froxlor/froxlor/commit/da810ea95393dfaec68a70e30b7c887c50563a7e"
},
{
"type": "PACKAGE",
"url": "https://github.com/froxlor/froxlor"
},
{
"type": "WEB",
"url": "https://huntr.dev/bounties/e50966cd-9222-46b9-aedc-1feb3f2a0b0e"
}
],
"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"
}
],
"summary": "Froxlor vulnerable to Path Traversal"
}
GHSA-GHRP-33PV-6WF9
Vulnerability from github – Published: 2022-05-02 03:27 – Updated: 2022-05-02 03:27Directory traversal vulnerability in arch.php in beLive 0.2.3 allows remote attackers to read arbitrary files via a .. (dot dot) in the arch parameter.
{
"affected": [],
"aliases": [
"CVE-2009-1649"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2009-05-16T18:30:00Z",
"severity": "HIGH"
},
"details": "Directory traversal vulnerability in arch.php in beLive 0.2.3 allows remote attackers to read arbitrary files via a .. (dot dot) in the arch parameter.",
"id": "GHSA-ghrp-33pv-6wf9",
"modified": "2022-05-02T03:27:08Z",
"published": "2022-05-02T03:27:08Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2009-1649"
},
{
"type": "WEB",
"url": "https://www.exploit-db.com/exploits/8680"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/35059"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/34968"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-GJ27-3482-R9V9
Vulnerability from github – Published: 2024-05-17 09:30 – Updated: 2024-05-17 09:31Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in artbees JupiterX allows PHP Local File Inclusion.This issue affects JupiterX: from n/a through 3.0.0.
{
"affected": [],
"aliases": [
"CVE-2023-32110"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-05-17T07:15:53Z",
"severity": "HIGH"
},
"details": "Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027) vulnerability in artbees JupiterX allows PHP Local File Inclusion.This issue affects JupiterX: from n/a through 3.0.0.",
"id": "GHSA-gj27-3482-r9v9",
"modified": "2024-05-17T09:31:00Z",
"published": "2024-05-17T09:30:59Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-32110"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/vulnerability/jupiterx/wordpress-jupiterx-theme-3-0-0-subscriber-local-file-inclusion-vulnerability?_s_id=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L",
"type": "CVSS_V3"
}
]
}
GHSA-GJ4P-3WH3-2RMF
Vulnerability from github – Published: 2017-12-21 00:47 – Updated: 2023-07-05 17:53lib/yard/core_ext/file.rb in the server in YARD before 0.9.11 does not block relative paths with an initial ../ sequence, which allows attackers to conduct directory traversal attacks and read arbitrary files.
{
"affected": [
{
"package": {
"ecosystem": "RubyGems",
"name": "yard"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.9.11"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2017-17042"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2020-06-16T21:37:31Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "`lib/yard/core_ext/file.rb` in the server in YARD before 0.9.11 does not block relative paths with an initial `../` sequence, which allows attackers to conduct directory traversal attacks and read arbitrary files.",
"id": "GHSA-gj4p-3wh3-2rmf",
"modified": "2023-07-05T17:53:08Z",
"published": "2017-12-21T00:47:25Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2017-17042"
},
{
"type": "WEB",
"url": "https://github.com/lsegal/yard/commit/b0217b3e30dc53d057b1682506333335975e62b4"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-gj4p-3wh3-2rmf"
},
{
"type": "PACKAGE",
"url": "https://github.com/lsegal/yard"
},
{
"type": "WEB",
"url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/yard/CVE-2017-17042.yml"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Arbitrary file read vulnerability in yard server"
}
GHSA-GJ5F-73VH-WPF7
Vulnerability from github – Published: 2025-10-10 06:30 – Updated: 2025-10-20 17:49Withdrawn Advisory
This advisory has been withdrawn because it does not discuss a valid vulnerability. This link is maintained to preserve external references.
Original Description
All versions of the package cross-zip are vulnerable to Directory Traversal via consecutive usage of zipSync() and unzipSync () functions that allow arguments such as __dirname. An attacker can access system files by selectively doing zip/unzip operations.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "cross-zip"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"last_affected": "4.0.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2025-11569"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2025-10-10T23:49:44Z",
"nvd_published_at": "2025-10-10T05:15:32Z",
"severity": "LOW"
},
"details": "### Withdrawn Advisory\nThis advisory has been withdrawn because it does not discuss a valid vulnerability. This link is maintained to preserve external references.\n\n### Original Description\nAll versions of the package cross-zip are vulnerable to Directory Traversal via consecutive usage of zipSync() and unzipSync () functions that allow arguments such as __dirname. An attacker can access system files by selectively doing zip/unzip operations.",
"id": "GHSA-gj5f-73vh-wpf7",
"modified": "2025-10-20T17:49:01Z",
"published": "2025-10-10T06:30:55Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-11569"
},
{
"type": "WEB",
"url": "https://gist.github.com/mcoimbra/9ab12a6187fac41d2fa7ba594ed535ac"
},
{
"type": "PACKAGE",
"url": "https://github.com/feross/cross-zip"
},
{
"type": "WEB",
"url": "https://github.com/feross/cross-zip/blob/eba335474e6142468bd8904f6456208db906d40d/index.js%23L94"
},
{
"type": "WEB",
"url": "https://security.snyk.io/vuln/SNYK-JS-CROSSZIP-6105396"
}
],
"schema_version": "1.4.0",
"severity": [],
"summary": "Withdrawn Advisory: cross-zip is vulnerable to Directory Traversal through selective use of zip/unzip operations",
"withdrawn": "2025-10-20T17:49:01Z"
}
GHSA-GJ9W-8JQJ-698C
Vulnerability from github – Published: 2023-05-09 15:30 – Updated: 2024-04-04 03:55A vulnerability has been identified in SCALANCE LPE9403 (All versions < V2.1). A path traversal vulnerability was found in the deviceinfo binary via the mac parameter. This could allow an authenticated attacker with access to the SSH interface on the affected device to read the contents of any file named address.
{
"affected": [],
"aliases": [
"CVE-2023-27409"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-05-09T13:15:16Z",
"severity": "LOW"
},
"details": "A vulnerability has been identified in SCALANCE LPE9403 (All versions \u003c V2.1). A path traversal vulnerability was found in the `deviceinfo` binary via the `mac` parameter. This could allow an authenticated attacker with access to the SSH interface on the affected device to read the contents of any file named `address`.",
"id": "GHSA-gj9w-8jqj-698c",
"modified": "2024-04-04T03:55:14Z",
"published": "2023-05-09T15:30:32Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-27409"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/pdf/ssa-325383.pdf"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-GJFG-22FP-RRXX
Vulnerability from github – Published: 2026-07-20 21:57 – Updated: 2026-07-20 21:57Summary
A Composer package declares its executables in the bin field of its composer.json. When Composer installs a package, it processes each bin entry and changes the file mode of the corresponding file so it is executable.
If a bin entry contains .. path segments, it can resolve to a path outside the package's own install directory. A malicious package can use this to make Composer run chmod against a file that already exists elsewhere on the machine. The resulting mode is world-readable and world-executable (0755 under the common umask of 022). This happens when the package is installed, e.g. during composer install, composer update, and composer require. Any dependency can trigger it, including a transitive dependency several levels deep.
The vulnerability changes file permissions only, and does not read, modify, or execute the contents of the target file, and it is not remote code execution. The impact is to confidentiality: a file with deliberately restrictive permissions, such as a private key at mode 0600, can be made readable by other users on the same host.
Am I affected?
We reviewed packagist.org data and found no evidence that any published package exploited this vulnerability. If you install packages only from packagist.org, you are not affected by any known exploitation.
You are potentially affected if all of the following are true:
- Your Composer project depends, directly or transitively, on a package you do not fully trust.
- A file you rely on for its restrictive permissions already exists at a path the Composer process can write to. Examples include SSH private keys,
.envfiles,~/.aws/credentials, and.netrc.
The most likely way to be affected is to add or update a dependency that is malicious or has been compromised, then run an install on a machine that holds sensitive, permission-restricted files.
Two points to note:
--no-scripts,--no-plugins, and anallow-pluginsallow-list do not prevent this. The permission change happens during normal binary installation, outside the plugin and script trust model.- Impact scales with privilege: As a regular user, only files owned by that user can be affected, which typically means your own secrets becoming readable by other local users on a shared machine. As root (for example, a CI container with no non-root user, or
sudo composer install), any file on the system can be affected, including system credential stores.
Patched versions
The fix makes Composer reject any package whose binary entry contains a .. path segment. During install/update the operation aborts before any file permission is changed, and the same check now also applies when a package is published to Packagist.org, so such packages are refused upstream.
Fixed in 2.2.29 (2.2 LTS line) and 2.10.2 (current 2.x line). Composer 1.x is end of life and will not be patched. 1.x users should upgrade to a patched 2.x release.
Workarounds
Upgrading to a patched release is the only complete fix. There is no configuration option that disables the vulnerable behavior.
{
"affected": [
{
"package": {
"ecosystem": "Packagist",
"name": "composer/composer"
},
"ranges": [
{
"events": [
{
"introduced": "2.3.0"
},
{
"fixed": "2.10.2"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Packagist",
"name": "composer/composer"
},
"ranges": [
{
"events": [
{
"introduced": "1.0.0"
},
{
"fixed": "2.2.29"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-59946"
],
"database_specific": {
"cwe_ids": [
"CWE-22",
"CWE-732"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-20T21:57:40Z",
"nvd_published_at": "2026-07-08T20:16:59Z",
"severity": "MODERATE"
},
"details": "## Summary\n\nA Composer package declares its executables in the `bin` field of its `composer.json`. When Composer installs a package, it processes each `bin` entry and changes the file mode of the corresponding file so it is executable.\n\nIf a `bin` entry contains `..` path segments, it can resolve to a path outside the package\u0027s own install directory. A malicious package can use this to make Composer run `chmod` against a file that already exists elsewhere on the machine. The resulting mode is world-readable and world-executable (0755 under the common umask of 022). This happens when the package is installed, e.g. during `composer install`, `composer update`, and `composer require`. Any dependency can trigger it, including a transitive dependency several levels deep.\n\nThe vulnerability *changes file permissions only, and does not read, modify, or execute the contents of the target file, and it is not remote code execution*. The impact is to confidentiality: a file with deliberately restrictive permissions, such as a private key at mode 0600, can be made readable by other users on the same host.\n\n## Am I affected?\n\nWe reviewed packagist.org data and found no evidence that any published package exploited this vulnerability. If you install packages only from packagist.org, you are not affected by any known exploitation.\n\nYou are potentially affected if *all* of the following are true:\n\n- Your Composer project depends, directly or transitively, on a package you do not fully trust.\n- A file you rely on for its restrictive permissions already exists at a path the Composer process can write to. Examples include SSH private keys, `.env` files, `~/.aws/credentials`, and `.netrc`.\n\nThe most likely way to be affected is to add or update a dependency that is malicious or has been compromised, then run an install on a machine that holds sensitive, permission-restricted files.\n\nTwo points to note:\n\n- `--no-scripts`, `--no-plugins`, and an `allow-plugins` allow-list do not prevent this. The permission change happens during normal binary installation, outside the plugin and script trust model.\n- Impact scales with privilege: As a regular user, only files owned by that user can be affected, which typically means your own secrets becoming readable by other local users on a shared machine. As root (for example, a CI container with no non-root user, or `sudo composer install`), any file on the system can be affected, including system credential stores.\n\n## Patched versions\n\nThe fix makes Composer reject any package whose binary entry contains a `..` path segment. During install/update the operation aborts before any file permission is changed, and the same check now also applies when a package is published to Packagist.org, so such packages are refused upstream.\n\nFixed in 2.2.29 (2.2 LTS line) and 2.10.2 (current 2.x line). Composer 1.x is end of life and will not be patched. 1.x users should upgrade to a patched 2.x release.\n\n## Workarounds\n\nUpgrading to a patched release is the only complete fix. There is no configuration option that disables the vulnerable behavior.",
"id": "GHSA-gjfg-22fp-rrxx",
"modified": "2026-07-20T21:57:40Z",
"published": "2026-07-20T21:57:40Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/composer/composer/security/advisories/GHSA-gjfg-22fp-rrxx"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-59946"
},
{
"type": "WEB",
"url": "https://github.com/composer/composer/commit/502c6c4f699802d9cf464728b3e8a95674f919a0"
},
{
"type": "WEB",
"url": "https://github.com/composer/composer/commit/c50b1efd13ebd73f6dca19b31424c5a02bf93cc1"
},
{
"type": "PACKAGE",
"url": "https://github.com/composer/composer"
},
{
"type": "WEB",
"url": "https://github.com/composer/composer/releases/tag/2.10.2"
},
{
"type": "WEB",
"url": "https://github.com/composer/composer/releases/tag/2.2.29"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Composer: Path traversal in package bin field lets dependencies chmod arbitrary host files"
}
GHSA-GJFX-9WX3-J6R7
Vulnerability from github – Published: 2022-05-13 01:24 – Updated: 2023-08-16 23:00Multiple directory traversal vulnerabilities in MyFaces JavaServer Faces (JSF) in Apache MyFaces Core 2.0.x before 2.0.12 and 2.1.x before 2.1.6 allow remote attackers to read arbitrary files via a .. (dot dot) in the (1) ln parameter to faces/javax.faces.resource/web.xml or (2) the PATH_INFO to faces/javax.faces.resource/.
{
"affected": [
{
"package": {
"ecosystem": "Maven",
"name": "org.apache.myfaces.core:myfaces-impl"
},
"ranges": [
{
"events": [
{
"introduced": "2.0.0"
},
{
"fixed": "2.0.12"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "org.apache.myfaces.core:myfaces-impl"
},
"ranges": [
{
"events": [
{
"introduced": "2.1.0"
},
{
"fixed": "2.1.6"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2011-4367"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2022-11-02T00:42:02Z",
"nvd_published_at": "2014-06-19T14:55:00Z",
"severity": "MODERATE"
},
"details": "Multiple directory traversal vulnerabilities in MyFaces JavaServer Faces (JSF) in Apache MyFaces Core 2.0.x before 2.0.12 and 2.1.x before 2.1.6 allow remote attackers to read arbitrary files via a `..` (dot dot) in the (1) ln parameter to `faces/javax.faces.resource/web.xml` or (2) the `PATH_INFO` to `faces/javax.faces.resource/`.",
"id": "GHSA-gjfx-9wx3-j6r7",
"modified": "2023-08-16T23:00:39Z",
"published": "2022-05-13T01:24:34Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2011-4367"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/73100"
},
{
"type": "WEB",
"url": "https://web.archive.org/web/20120213042504/http://www.securityfocus.com/bid/51939"
},
{
"type": "WEB",
"url": "http://mail-archives.apache.org/mod_mbox/myfaces-announce/201202.mbox/%3C4F33ED1F.4070007%40apache.org%3E"
},
{
"type": "WEB",
"url": "http://seclists.org/fulldisclosure/2012/Feb/150"
}
],
"schema_version": "1.4.0",
"severity": [],
"summary": "Apache MyFaces Vulnerable to Path Traversal"
}
GHSA-GJFX-RQ6J-6V2P
Vulnerability from github – Published: 2022-08-28 00:00 – Updated: 2022-09-02 00:01Zaver through 2020-12-15 allows directory traversal via the GET /.. substring.
{
"affected": [],
"aliases": [
"CVE-2022-38794"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-08-27T21:15:00Z",
"severity": "HIGH"
},
"details": "Zaver through 2020-12-15 allows directory traversal via the GET /.. substring.",
"id": "GHSA-gjfx-rq6j-6v2p",
"modified": "2022-09-02T00:01:05Z",
"published": "2022-08-28T00:00:26Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-38794"
},
{
"type": "WEB",
"url": "https://github.com/zyearn/zaver/issues/22"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
Mitigation MIT-5.1
Strategy: Input Validation
- Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
- When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434.
- Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would be removed from the original string, but the remaining characters would still form the "../" string.
Mitigation MIT-15
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Mitigation MIT-20.1
Strategy: Input Validation
- Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
- Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59). This includes:
- realpath() in C
- getCanonicalPath() in Java
- GetFullPath() in ASP.NET
- realpath() or abs_path() in Perl
- realpath() in PHP
Mitigation MIT-4
Strategy: Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
Mitigation MIT-29
Strategy: Firewall
Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].
Mitigation MIT-17
Strategy: Environment Hardening
Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
Mitigation MIT-21.1
Strategy: Enforcement by Conversion
- When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
- For example, ID 1 could map to "inbox.txt" and ID 2 could map to "profile.txt". Features such as the ESAPI AccessReferenceMap [REF-185] provide this capability.
Mitigation MIT-22
Strategy: Sandbox or Jail
- Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.
- OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations.
- This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise.
- Be careful to avoid CWE-243 and other weaknesses related to jails.
Mitigation MIT-34
Strategy: Attack Surface Reduction
- Store library, include, and utility files outside of the web document root, if possible. Otherwise, store them in a separate directory and use the web server's access control capabilities to prevent attackers from directly requesting them. One common practice is to define a fixed constant in each calling program, then check for the existence of the constant in the library/include file; if the constant does not exist, then the file was directly requested, and it can exit immediately.
- This significantly reduces the chance of an attacker being able to bypass any protection mechanisms that are in the base program but not in the include files. It will also reduce the attack surface.
Mitigation MIT-39
- Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success.
- If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files.
- Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not.
- In the context of path traversal, error messages which disclose path information can help attackers craft the appropriate attack strings to move through the file system hierarchy.
Mitigation MIT-16
Strategy: Environment Hardening
When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
CAPEC-126: Path Traversal
An adversary uses path manipulation methods to exploit insufficient input validation of a target to obtain access to data that should be not be retrievable by ordinary well-formed requests. A typical variety of this attack involves specifying a path to a desired file together with dot-dot-slash characters, resulting in the file access API or function traversing out of the intended directory structure and into the root file system. By replacing or modifying the expected path information the access function or API retrieves the file desired by the attacker. These attacks either involve the attacker providing a complete path to a targeted file or using control characters (e.g. path separators (/ or \) and/or dots (.)) to reach desired directories or files.
CAPEC-64: Using Slashes and URL Encoding Combined to Bypass Validation Logic
This attack targets the encoding of the URL combined with the encoding of the slash characters. An attacker can take advantage of the multiple ways of encoding a URL and abuse the interpretation of the URL. A URL may contain special character that need special syntax handling in order to be interpreted. Special characters are represented using a percentage character followed by two digits representing the octet code of the original character (%HEX-CODE). For instance US-ASCII space character would be represented with %20. This is often referred as escaped ending or percent-encoding. Since the server decodes the URL from the requests, it may restrict the access to some URL paths by validating and filtering out the URL requests it received. An attacker will try to craft an URL with a sequence of special characters which once interpreted by the server will be equivalent to a forbidden URL. It can be difficult to protect against this attack since the URL can contain other format of encoding such as UTF-8 encoding, Unicode-encoding, etc.
CAPEC-76: Manipulating Web Input to File System Calls
An attacker manipulates inputs to the target software which the target software passes to file system calls in the OS. The goal is to gain access to, and perhaps modify, areas of the file system that the target software did not intend to be accessible.
CAPEC-78: Using Escaped Slashes in Alternate Encoding
This attack targets the use of the backslash in alternate encoding. An adversary can provide a backslash as a leading character and causes a parser to believe that the next character is special. This is called an escape. By using that trick, the adversary tries to exploit alternate ways to encode the same character which leads to filter problems and opens avenues to attack.
CAPEC-79: Using Slashes in Alternate Encoding
This attack targets the encoding of the Slash characters. An adversary would try to exploit common filtering problems related to the use of the slashes characters to gain access to resources on the target host. Directory-driven systems, such as file systems and databases, typically use the slash character to indicate traversal between directories or other container components. For murky historical reasons, PCs (and, as a result, Microsoft OSs) choose to use a backslash, whereas the UNIX world typically makes use of the forward slash. The schizophrenic result is that many MS-based systems are required to understand both forms of the slash. This gives the adversary many opportunities to discover and abuse a number of common filtering problems. The goal of this pattern is to discover server software that only applies filters to one version, but not the other.