erkzeug 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.
Configuration 1 (hide)
| AND |
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03 Dec 2025, 15:27
| Type | Values Removed | Values Added |
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| First Time |
Microsoft windows
Microsoft Palletsprojects werkzeug Palletsprojects |
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| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 5.3 |
| CPE | cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:* cpe:2.3:a:palletsprojects:werkzeug:*:*:*:*:*:*:*:* |
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| References | () https://github.com/pallets/werkzeug/commit/4b833376a45c323a189cd11d2362bcffdb1c0c13 - Patch | |
| References | () https://github.com/pallets/werkzeug/releases/tag/3.1.4 - Release Notes | |
| References | () https://github.com/pallets/werkzeug/security/advisories/GHSA-hgf8-39gv-g3f2 - Vendor Advisory |
29 Nov 2025, 03:16
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| New CVE |
Published : 2025-11-29 03:16
Updated : 2025-12-03 15:27
NVD link : CVE-2025-66221
Mitre link : CVE-2025-66221
CVE.ORG link : CVE-2025-66221
JSON object : View
Improper Handling of Windows Device Names