Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.5, Werkzeug's safe_join function allows path segments with Windows device names that have file extensions or trailing spaces. On Windows, there are special device names such as CON, AUX, etc that are implicitly present and readable in every directory. Windows still accepts them with any file extension, such as CON.txt, or trailing spaces such as CON. This issue has been patched in version 3.1.5.
History

Fri, 09 Jan 2026 13:30:00 +0000

Type Values Removed Values Added
First Time appeared Microsoft
Microsoft windows
Palletsprojects
Palletsprojects werkzeug
Vendors & Products Microsoft
Microsoft windows
Palletsprojects
Palletsprojects werkzeug

Thu, 08 Jan 2026 19:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 08 Jan 2026 18:45:00 +0000

Type Values Removed Values Added
Description Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.5, Werkzeug's safe_join function allows path segments with Windows device names that have file extensions or trailing spaces. On Windows, there are special device names such as CON, AUX, etc that are implicitly present and readable in every directory. Windows still accepts them with any file extension, such as CON.txt, or trailing spaces such as CON. This issue has been patched in version 3.1.5.
Title Werkzeug safe_join() allows Windows special device names with compound extensions
Weaknesses CWE-67
References
Metrics cvssV4_0

{'score': 6.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-01-08T18:50:34.504Z

Reserved: 2026-01-05T16:44:16.367Z

Link: CVE-2026-21860

cve-icon Vulnrichment

Updated: 2026-01-08T18:50:31.180Z

cve-icon NVD

Status : Received

Published: 2026-01-08T19:15:59.000

Modified: 2026-01-08T19:15:59.000

Link: CVE-2026-21860

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-01-09T13:24:11Z