Bug 2417789 (CVE-2025-66221) - CVE-2025-66221 Werkzeug: Werkzeug: Denial of service via Windows device names in path segments
Summary: CVE-2025-66221 Werkzeug: Werkzeug: Denial of service via Windows device names...
Keywords:
Status: NEW
Alias: CVE-2025-66221
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2025-11-29 03:01 UTC by OSIDB Bzimport
Modified: 2025-12-17 04:49 UTC (History)
3 users (show)

Fixed In Version:
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Description OSIDB Bzimport 2025-11-29 03:01:45 UTC 
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.
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