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-7975-2QR9-G542
Vulnerability from github – Published: 2025-01-09 03:30 – Updated: 2025-05-03 00:30The Permission Model assumes that any path starting with two backslashes \ has a four-character prefix that can be ignored, which is not always true. This subtle bug leads to vulnerable edge cases.
{
"affected": [],
"aliases": [
"CVE-2024-37372"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-01-09T01:15:08Z",
"severity": "LOW"
},
"details": "The Permission Model assumes that any path starting with two backslashes \\ has a four-character prefix that can be ignored, which is not always true. This subtle bug leads to vulnerable edge cases.",
"id": "GHSA-7975-2qr9-g542",
"modified": "2025-05-03T00:30:32Z",
"published": "2025-01-09T03:30:48Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-37372"
},
{
"type": "WEB",
"url": "https://security.netapp.com/advisory/ntap-20250502-0010"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2024/07/11/6"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2024/07/19/3"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-799H-MC82-P9WC
Vulnerability from github – Published: 2022-05-17 05:47 – Updated: 2022-05-17 05:47Directory traversal vulnerability in ADMIN/login.php in NetArtMEDIA WebSiteAdmin allows remote emote attackers to include and execute arbitrary local files via directory traversal sequences in the lng parameter.
{
"affected": [],
"aliases": [
"CVE-2010-3688"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2010-09-29T17:00:00Z",
"severity": "HIGH"
},
"details": "Directory traversal vulnerability in ADMIN/login.php in NetArtMEDIA WebSiteAdmin allows remote emote attackers to include and execute arbitrary local files via directory traversal sequences in the lng parameter.",
"id": "GHSA-799h-mc82-p9wc",
"modified": "2022-05-17T05:47:59Z",
"published": "2022-05-17T05:47:59Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2010-3688"
},
{
"type": "WEB",
"url": "http://pridels-team.blogspot.com/2010/09/netartmedia-real-estate-portal-v20-xss.html"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-79C8-PC25-J96R
Vulnerability from github – Published: 2022-02-09 00:00 – Updated: 2022-02-09 00:00Directory traversal in /northstar/Common/NorthFileManager/fileManagerObjects.jsp Northstar Technologies Inc NorthStar Club Management 6.3 allows remote unauthenticated users to browse and list the directories across the entire filesystem of the host of the web application.
{
"affected": [],
"aliases": [
"CVE-2021-29398"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-02-04T19:15:00Z",
"severity": "MODERATE"
},
"details": "Directory traversal in /northstar/Common/NorthFileManager/fileManagerObjects.jsp Northstar Technologies Inc NorthStar Club Management 6.3 allows remote unauthenticated users to browse and list the directories across the entire filesystem of the host of the web application.",
"id": "GHSA-79c8-pc25-j96r",
"modified": "2022-02-09T00:00:38Z",
"published": "2022-02-09T00:00:38Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-29398"
},
{
"type": "WEB",
"url": "https://Ardent-Security.com"
},
{
"type": "WEB",
"url": "https://ardent-security.com/en/advisory/asa-2021-06"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-79HP-68X4-58HX
Vulnerability from github – Published: 2022-05-24 22:28 – Updated: 2022-05-24 22:28The directory list page parameter of the Orca HCM digital learning platform fails to filter special characters properly. Remote attackers can access the system directory thru Path Traversal with users’ privileges.
{
"affected": [],
"aliases": [
"CVE-2021-35968"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2021-07-19T12:15:00Z",
"severity": "MODERATE"
},
"details": "The directory list page parameter of the Orca HCM digital learning platform fails to filter special characters properly. Remote attackers can access the system directory thru Path Traversal with users\u2019 privileges.",
"id": "GHSA-79hp-68x4-58hx",
"modified": "2022-05-24T22:28:22Z",
"published": "2022-05-24T22:28:22Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-35968"
},
{
"type": "WEB",
"url": "https://www.chtsecurity.com/news/ba7b3ae7-14f3-4970-b3f6-4d97d8c7ea25"
},
{
"type": "WEB",
"url": "https://www.twcert.org.tw/tw/cp-132-4928-7e87b-1.html"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-79HX-3FP8-HJ66
Vulnerability from github – Published: 2025-09-17 20:11 – Updated: 2025-09-26 16:18Impact
A peer exposes the gRPC API and HTTP API for consumption by other peers. These APIs allow peers to send requests that force the recipient peer to create files in arbitrary file system locations, and to read arbitrary files. This allows peers to steal other peers’ secret data and to gain remote code execution (RCE) capabilities on the peer’s machine.
file, err := os.OpenFile(t.DataFilePath, os.O_RDWR, defaultFileMode)
if err != nil {
return 0, err
}
defer file.Close()
if _, err = file.Seek(req.Range.Start, io.SeekStart); err != nil {
return 0, err
}
n, err := io.Copy(file, io.LimitReader(req.Reader, req.Range.Length))
Patches
- Dragonfy v2.1.0 and above.
Workarounds
There are no effective workarounds, beyond upgrading.
References
A third party security audit was performed by Trail of Bits, you can see the full report.
If you have any questions or comments about this advisory, please email us at dragonfly-maintainers@googlegroups.com.
{
"affected": [
{
"package": {
"ecosystem": "Go",
"name": "github.com/dragonflyoss/dragonfly"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.1.0"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Go",
"name": "d7y.io/dragonfly/v2"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.1.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2025-59352"
],
"database_specific": {
"cwe_ids": [
"CWE-202",
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2025-09-17T20:11:13Z",
"nvd_published_at": "2025-09-17T20:15:37Z",
"severity": "MODERATE"
},
"details": "### Impact\nA peer exposes the gRPC API and HTTP API for consumption by other peers. These APIs allow peers to send requests that force the recipient peer to create files in arbitrary file system locations, and to read arbitrary files. This allows peers to steal other peers\u2019 secret data and to gain remote code execution (RCE) capabilities on the peer\u2019s machine.\n\n```golang\nfile, err := os.OpenFile(t.DataFilePath, os.O_RDWR, defaultFileMode)\nif err != nil {\n return 0, err\n}\ndefer file.Close()\nif _, err = file.Seek(req.Range.Start, io.SeekStart); err != nil {\n return 0, err\n}\nn, err := io.Copy(file, io.LimitReader(req.Reader, req.Range.Length))\n```\n\n### Patches\n\n- Dragonfy v2.1.0 and above.\n\n### Workarounds\n\nThere are no effective workarounds, beyond upgrading.\n\n### References\n\nA third party security audit was performed by Trail of Bits, you can see the [full report](https://github.com/dragonflyoss/dragonfly/blob/main/docs/security/dragonfly-comprehensive-report-2023.pdf).\n\nIf you have any questions or comments about this advisory, please email us at [dragonfly-maintainers@googlegroups.com](mailto:dragonfly-maintainers@googlegroups.com).",
"id": "GHSA-79hx-3fp8-hj66",
"modified": "2025-09-26T16:18:51Z",
"published": "2025-09-17T20:11:13Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/dragonflyoss/dragonfly/security/advisories/GHSA-79hx-3fp8-hj66"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-59352"
},
{
"type": "PACKAGE",
"url": "https://github.com/dragonflyoss/dragonfly"
},
{
"type": "WEB",
"url": "https://github.com/dragonflyoss/dragonfly/blob/main/docs/security/dragonfly-comprehensive-report-2023.pdf"
},
{
"type": "WEB",
"url": "https://pkg.go.dev/vuln/GO-2025-3961"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H/E:P",
"type": "CVSS_V4"
}
],
"summary": "DragonFly vulnerable to arbitrary file read and write on a peer machine"
}
GHSA-79JF-625M-7XJF
Vulnerability from github – Published: 2022-04-29 03:00 – Updated: 2022-04-29 03:00Directory traversal vulnerability in the map feature (tiki-map.phtml) in Tiki CMS/Groupware (TikiWiki) 1.8.1 and earlier allows remote attackers to determine the existence of arbitrary files via .. (dot dot) sequences in the mapfile parameter.
{
"affected": [],
"aliases": [
"CVE-2004-1927"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2004-04-11T04:00:00Z",
"severity": "MODERATE"
},
"details": "Directory traversal vulnerability in the map feature (tiki-map.phtml) in Tiki CMS/Groupware (TikiWiki) 1.8.1 and earlier allows remote attackers to determine the existence of arbitrary files via .. (dot dot) sequences in the mapfile parameter.",
"id": "GHSA-79jf-625m-7xjf",
"modified": "2022-04-29T03:00:28Z",
"published": "2022-04-29T03:00:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2004-1927"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/15848"
},
{
"type": "WEB",
"url": "http://marc.info/?l=bugtraq\u0026m=108180073206947\u0026w=2"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/11344"
},
{
"type": "WEB",
"url": "http://tikiwiki.org/tiki-read_article.php?articleId=66"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/10100"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-79MG-HFRX-5889
Vulnerability from github – Published: 2025-02-18 06:35 – Updated: 2026-04-08 18:33The Actionwear products sync plugin for WordPress is vulnerable to Full Path Disclosure in all versions up to, and including, 2.3.0. This is due the composer-setup.php file being publicly accessible with 'display_errors' set to true. This makes it possible for unauthenticated attackers to retrieve the full path of the web application, which can be used to aid other attacks. The information displayed is not useful on its own, and requires another vulnerability to be present for damage to an affected website.
{
"affected": [],
"aliases": [
"CVE-2024-13535"
],
"database_specific": {
"cwe_ids": [
"CWE-209",
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-02-18T05:15:12Z",
"severity": "MODERATE"
},
"details": "The Actionwear products sync plugin for WordPress is vulnerable to Full Path Disclosure in all versions up to, and including, 2.3.0. This is due the composer-setup.php file being publicly accessible with \u0027display_errors\u0027 set to true. This makes it possible for unauthenticated attackers to retrieve the full path of the web application, which can be used to aid other attacks. The information displayed is not useful on its own, and requires another vulnerability to be present for damage to an affected website.",
"id": "GHSA-79mg-hfrx-5889",
"modified": "2026-04-08T18:33:48Z",
"published": "2025-02-18T06:35:38Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-13535"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/actionwear-products-sync/trunk/composer-setup.php"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/changeset?sfp_email=\u0026sfph_mail=\u0026reponame=\u0026old=3241824%40actionwear-products-sync\u0026new=3241824%40actionwear-products-sync\u0026sfp_email=\u0026sfph_mail="
},
{
"type": "WEB",
"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/6dbf9689-c812-4b7c-9df3-c4639aae3357?source=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-79P8-4CWQ-RHQH
Vulnerability from github – Published: 2018-07-23 20:40 – Updated: 2023-09-05 23:24Affected versions of jn_jj_server resolve relative file paths, resulting in a directory traversal vulnerability. A malicious actor can use this vulnerability to access files outside of the intended directory root, which may result in the disclosure of private files on the vulnerable system.
Example request:
GET /../../../../../../../../../../etc/passwd HTTP/1.1
host:foo
Recommendation
No patch is available for this vulnerability.
It is recommended that the package is only used for local development, and if the functionality is needed for production, a different package is used instead.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "jn_jj_server"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"last_affected": "0.0.8"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2017-16210"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2020-06-16T21:22:18Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "Affected versions of `jn_jj_server` resolve relative file paths, resulting in a directory traversal vulnerability. A malicious actor can use this vulnerability to access files outside of the intended directory root, which may result in the disclosure of private files on the vulnerable system.\n\n**Example request:**\n```http\nGET /../../../../../../../../../../etc/passwd HTTP/1.1\nhost:foo\n```\n\n\n## Recommendation\n\nNo patch is available for this vulnerability.\n\nIt is recommended that the package is only used for local development, and if the functionality is needed for production, a different package is used instead.",
"id": "GHSA-79p8-4cwq-rhqh",
"modified": "2023-09-05T23:24:25Z",
"published": "2018-07-23T20:40:07Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2017-16210"
},
{
"type": "WEB",
"url": "https://github.com/JacksonGL/NPM-Vuln-PoC/blob/master/directory-traversal/jn_jj_server"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-79p8-4cwq-rhqh"
},
{
"type": "WEB",
"url": "https://www.npmjs.com/advisories/424"
}
],
"schema_version": "1.4.0",
"severity": [],
"summary": "Directory Traversal in jn_jj_server"
}
GHSA-79PH-745M-6WXQ
Vulnerability from github – Published: 2026-06-16 17:35 – Updated: 2026-07-20 13:41Summary
Langflow is vulnerable to Path Traversal in the Knowledge Bases API (POST /api/v1/knowledge_bases). This occurs because user-supplied knowledge base names are used directly to create file paths without proper sanitization or containment checks. An authenticated attacker can exploit this flaw to create directories and write files anywhere on the server's filesystem.
Details
The vulnerability exists in the create_knowledge_base function within src/backend/base/langflow/api/v1/knowledge_bases.py.
This function constructs file paths directly from the user-supplied name field without sanitization. The value is concatenated with the user's base directory and passed directly to kb_path.mkdir(). Immediately following the directory creation, the application writes embedding_metadata.json and schema.json into this attacker-controlled path.
PoC (Proof of Concept)
For the Create endpoint, an attacker can supply traversal sequences or absolute paths in the name field:
../victim_user/evil_kb
or
/tmp/pwned
This forces kb_path.mkdir() to create directories and write specific application files (embedding_metadata.json and schema.json) at any reachable path on the server.
Impact
Any Langflow instance exposing this endpoint to authenticated users is vulnerable. This exposes the server to:
* Cross-user data compromise: Creation of directories and files within another tenant's knowledge base space.
* Arbitrary filesystem manipulation: Directory creation at any path on the server where the application has write permissions (e.g., /app/data).
* Data overwrite: Overwriting existing embedding_metadata.json and schema.json files in attacker-targeted paths, potentially corrupting existing knowledge bases.
Fixes
The issue was addressed in PR #12337. The fix introduces the _validate_kb_path_containment() helper function, which uses Path.is_relative_to() instead of startswith() to enforce strict path boundaries and prevent prefix-ambiguity bugs. This helper is applied before any filesystem operations. Regression tests were added to verify that traversal payloads return a 403 Forbidden.
Acknowledgements
Thanks to the security researchers who responsibly disclosed this vulnerability: * @ddlxstudio * @nekros1xx
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 1.8.4"
},
"package": {
"ecosystem": "PyPI",
"name": "langflow"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.9.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-42867"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2026-06-16T17:35:09Z",
"nvd_published_at": "2026-06-23T17:16:58Z",
"severity": "MODERATE"
},
"details": "## Summary\nLangflow is vulnerable to Path Traversal in the Knowledge Bases API (`POST /api/v1/knowledge_bases`). This occurs because user-supplied knowledge base names are used directly to create file paths without proper sanitization or containment checks. An authenticated attacker can exploit this flaw to create directories and write files anywhere on the server\u0027s filesystem.\n\n## Details\nThe vulnerability exists in the `create_knowledge_base` function within `src/backend/base/langflow/api/v1/knowledge_bases.py`. \n\nThis function constructs file paths directly from the user-supplied `name` field without sanitization. The value is concatenated with the user\u0027s base directory and passed directly to `kb_path.mkdir()`. Immediately following the directory creation, the application writes `embedding_metadata.json` and `schema.json` into this attacker-controlled path.\n\n## PoC (Proof of Concept)\nFor the **Create** endpoint, an attacker can supply traversal sequences or absolute paths in the `name` field:\n\n`../victim_user/evil_kb`\nor\n`/tmp/pwned`\n\nThis forces `kb_path.mkdir()` to create directories and write specific application files (`embedding_metadata.json` and `schema.json`) at any reachable path on the server.\n\n## Impact\nAny Langflow instance exposing this endpoint to authenticated users is vulnerable. This exposes the server to:\n* **Cross-user data compromise:** Creation of directories and files within another tenant\u0027s knowledge base space.\n* **Arbitrary filesystem manipulation:** Directory creation at any path on the server where the application has write permissions (e.g., `/app/data`).\n* **Data overwrite:** Overwriting existing `embedding_metadata.json` and `schema.json` files in attacker-targeted paths, potentially corrupting existing knowledge bases.\n\n## Fixes\nThe issue was addressed in **PR #12337**. The fix introduces the `_validate_kb_path_containment()` helper function, which uses `Path.is_relative_to()` instead of `startswith()` to enforce strict path boundaries and prevent prefix-ambiguity bugs. This helper is applied before any filesystem operations. Regression tests were added to verify that traversal payloads return a `403 Forbidden`.\n\n## Acknowledgements\nThanks to the security researchers who responsibly disclosed this vulnerability:\n* @ddlxstudio\n* @nekros1xx",
"id": "GHSA-79ph-745m-6wxq",
"modified": "2026-07-20T13:41:52Z",
"published": "2026-06-16T17:35:09Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/langflow-ai/langflow/security/advisories/GHSA-79ph-745m-6wxq"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42867"
},
{
"type": "WEB",
"url": "https://github.com/langflow-ai/langflow/pull/12337"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-79ph-745m-6wxq"
},
{
"type": "PACKAGE",
"url": "https://github.com/langflow-ai/langflow"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/langflow/PYSEC-2026-2566.yaml"
},
{
"type": "WEB",
"url": "https://pypi.org/project/langflow"
}
],
"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"
}
],
"summary": "Langflow: Path Traversal in Knowledge Bases API via Creation Endpoint"
}
GHSA-79PP-3MFJ-FP8J
Vulnerability from github – Published: 2022-05-02 03:28 – Updated: 2022-05-02 03:28Multiple directory traversal vulnerabilities in index.php in Catviz 0.4.0 Beta 1 allow remote attackers to read arbitrary files via a .. (dot dot) in the (1) webpages_form or (2) userman_form parameter.
{
"affected": [],
"aliases": [
"CVE-2009-1748"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2009-05-22T11:52:00Z",
"severity": "HIGH"
},
"details": "Multiple directory traversal vulnerabilities in index.php in Catviz 0.4.0 Beta 1 allow remote attackers to read arbitrary files via a .. (dot dot) in the (1) webpages_form or (2) userman_form parameter.",
"id": "GHSA-79pp-3mfj-fp8j",
"modified": "2022-05-02T03:28:14Z",
"published": "2022-05-02T03:28:14Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2009-1748"
},
{
"type": "WEB",
"url": "https://www.exploit-db.com/exploits/8745"
},
{
"type": "WEB",
"url": "http://osvdb.org/54657"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/35042"
}
],
"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.