Vulnerability Description
Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.4, 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. This issue has been patched in version 3.1.4.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Palletsprojects | Werkzeug | < 3.1.4 |
| Microsoft | Windows | - |
Related Weaknesses (CWE)
References
- https://github.com/pallets/werkzeug/commit/4b833376a45c323a189cd11d2362bcffdb1c0Patch
- https://github.com/pallets/werkzeug/releases/tag/3.1.4Release Notes
- https://github.com/pallets/werkzeug/security/advisories/GHSA-hgf8-39gv-g3f2Vendor Advisory
FAQ
What is CVE-2025-66221?
CVE-2025-66221 is a vulnerability with a CVSS score of 5.3 (MEDIUM). Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.4, Werkzeug's safe_join function allows path segments with Windows device names. On Windows, there are special device nam...
How severe is CVE-2025-66221?
CVE-2025-66221 has been rated MEDIUM with a CVSS base score of 5.3/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2025-66221?
Check the references section above for vendor advisories and patch information. Affected products include: Palletsprojects Werkzeug, Microsoft Windows.