CVE-2025-66221
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.
Published:Nov 29, 2025
Last Modified:Dec 3, 2025
EPS:Nov 29, 2025
EPSS Score:0.00044
CVSS Score:5.3
Affected Products
Vendor
Product
Action
Vendor
Microsoft
Product
Windows
Microsoft
Windows
Vendor
Palletsprojects
Product
Werkzeug
Palletsprojects
Werkzeug
Exploits
No exploit reference
Common Weakness Enumeration
Common Attack Pattern Enumeration and Classification (CAPEC)
No CAPEC recorded yet
Related CVEs
Common Vulnerability Scoring System
Attack Vector
Network
Adjacent
Local
Physical
Privileges Required
None
Low
High
User Interaction
None
Required
Scope
Unchanged
Changed
Confidentiality
None
Low
High
Integrity
None
Low
High
Availability
None
Low
High
