Werkzeug safe_join() allows Windows special device names

Werkzeug's safejoin function allows Windows device names as filenames when they have an empty ADS marker on NTFS. This was previously reported as https://github.com/pallets/werkzeug/security/advisories/GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact Windows allows...

GHSA-G6X2-HCCM-HH4M Werkzeug safe_join() allows Windows special device names

Werkzeug's safejoin function allows Windows device names as filenames when they have an empty ADS marker on NTFS. This was previously reported as https://github.com/pallets/werkzeug/security/advisories/GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact Windows allows...

EUVD-2026-1425

Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.5, Werkzeug's safejoin 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...

Werkzeug safe_join() allows Windows special device names

Werkzeug's safejoin 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. sendfromdirectory uses safejoin to safely serve files at user-specified paths under a director...