GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

BREW-KEEPER-COMMANDER-CV… (GHSA-HGF8-39GV-G3F2)

Vulnerability from osv_homebrew – Published: 2026-08-13 17:01 – Updated: 2026-09-17 18:04 – Source website
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
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "fix": "bump",
        "range_state": "fixed",
        "resource": "werkzeug",
        "resource_purl": "pkg:pypi/werkzeug@3.1.8",
        "upstream_fixed_in": "3.1.4"
      },
      "package": {
        "ecosystem": "Homebrew",
        "name": "keeper-commander",
        "purl": "pkg:brew/keeper-commander"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "17.0.20"
            },
            {
              "fixed": "17.1.15_1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "confidence": "high",
    "source": "matched",
    "strategy": "registry",
    "upstream_evidence": [
      {
        "ecosystem": "PyPI",
        "key": "pkg:pypi/werkzeug@3.1.8",
        "name": "werkzeug",
        "resource": "werkzeug",
        "strategy": "registry",
        "subject_version": "3.1.8"
      }
    ]
  },
  "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": "BREW-keeper-commander-CVE-2025-66221",
  "modified": "2026-09-17T18:04:36Z",
  "published": "2026-08-13T17:01:22Z",
  "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": "1.7.3",
  "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",
  "upstream": [
    "GHSA-hgf8-39gv-g3f2",
    "CVE-2025-66221",
    "PYSEC-2026-2046"
  ]
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.