{
  "canonical_id": "werkzeug--CVE-2026-27199",
  "system_id": "werkzeug",
  "display_name": "Werkzeug",
  "category": "frameworks",
  "advisory_mode": "core",
  "title": " Werkzeug safe_join() allows Windows special device names",
  "summary": "Werkzeug's `safe_join` function allows Windows device names as filenames if when preceded by other path segments.\n\nThis was previously reported as https://github.com/pallets/werkzeug/security/advisories/GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact that `safe_join` accepts paths with multiple segments, such as `example/NUL`.\n\n`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.",
  "published_at": "2026-02-19T20:32:45Z",
  "updated_at": "2026-02-23T23:43:27.690386Z",
  "severity": "medium",
  "cvss_score": 4.0,
  "exploit_status": "unknown",
  "source_confidence": "official",
  "official_source_url": "https://github.com/pallets/werkzeug/security/advisories/GHSA-29vq-49wr-vm6x",
  "secondary_source_urls": [
    "https://nvd.nist.gov/vuln/detail/CVE-2026-27199",
    "https://github.com/pallets/werkzeug/commit/f407712fdc60a09c2b3f4fe7db557703e5d9338d",
    "https://github.com/pallets/werkzeug",
    "https://github.com/pallets/werkzeug/releases/tag/3.1.6"
  ],
  "aliases": [
    "CVE-2026-27199",
    "GHSA-29vq-49wr-vm6x"
  ],
  "cve_ids": [
    "CVE-2026-27199"
  ],
  "ghsa_ids": [
    "GHSA-29vq-49wr-vm6x"
  ],
  "osv_ids": [
    "GHSA-29vq-49wr-vm6x"
  ],
  "affected_versions": [
    "0.1",
    "0.10",
    "0.10.1",
    "0.10.2",
    "0.10.3",
    "0.10.4",
    "0.11",
    "0.11.1",
    "0.11.10",
    "0.11.11",
    "0.11.12",
    "0.11.13",
    "0.11.14",
    "0.11.15",
    "0.11.2",
    "0.11.3",
    "0.11.4",
    "0.11.5",
    "0.11.6",
    "0.11.7",
    "introduced=0, fixed<3.1.6"
  ],
  "fixed_versions": [
    "3.1.6"
  ],
  "package_name": "werkzeug",
  "render_markdown": true,
  "case_path": "07-framework-security/frameworks/werkzeug/cases/werkzeug-cve-2026-27199.md",
  "secure_code_topics": [
    "proxy-trust-boundary",
    "request-smuggling-boundary"
  ],
  "status": "generated",
  "triage_reasons": [],
  "verification_status": "triage-manual",
  "verification_mode": "synthetic",
  "last_verified_at": null,
  "last_run_id": null,
  "evidence_bundle": null,
  "historical_status": null,
  "latest_status": null,
  "browser_evidence": {
    "required": false,
    "present": false,
    "refs": []
  },
  "repro_profile_id": "proxy-boundary-generic",
  "artifact_mode": "synthetic",
  "blocked_reason": null,
  "metadata": {
    "source_names": [
      "OSV Werkzeug"
    ],
    "source_kinds": [
      "osv-batch"
    ],
    "candidate_count": 1
  }
}