GHSA-HGF8-39GV-G3F2

Vulnerability from github – Published: 2025-12-02 00:27 – Updated: 2025-12-02 00:27
VLAI?
Summary
Werkzeug safe_join() allows Windows special device names
Details

Werkzeug's safe_join function allows path segments with Windows device names. On Windows, there are special device names such as CON, AUX, etc that are implicitly present and readable in every directory. send_from_directory uses safe_join to safely serve files at user-specified paths under a directory. If the application is running on Windows, and the requested path ends with a special device name, the file will be opened successfully, but reading will hang indefinitely.

Severity ?
6.3 (Medium)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "werkzeug"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.1.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-66221"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-67"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-12-02T00:27:38Z",
    "nvd_published_at": "2025-11-29T03:16:00Z",
    "severity": "MODERATE"
  },
  "details": "Werkzeug\u0027s `safe_join` function allows path segments with Windows device names. On Windows, there are special device names such as `CON`, `AUX`, etc that are implicitly present and readable in every directory. `send_from_directory` uses `safe_join` to safely serve files at user-specified paths under a directory. If the application is running on Windows, and the requested path ends with a special device name, the file will be opened successfully, but reading will hang indefinitely.",
  "id": "GHSA-hgf8-39gv-g3f2",
  "modified": "2025-12-02T00:27:38Z",
  "published": "2025-12-02T00:27:38Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/pallets/werkzeug/security/advisories/GHSA-hgf8-39gv-g3f2"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-66221"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pallets/werkzeug/commit/4b833376a45c323a189cd11d2362bcffdb1c0c13"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/pallets/werkzeug"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pallets/werkzeug/releases/tag/3.1.4"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Werkzeug safe_join() allows Windows special device names"
}


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