CVE-2026-21860 — Werkzeug safe_join() allows Windows special device names with compound extensions
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 ext…
Published: 2026-01-08 · CVSS: 6.3 · CVSS 4.0
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7