CVE-2026-27199 (GCVE-0-2026-27199)

Vulnerability from cvelistv5 – Published: 2026-02-21 05:15 – Updated: 2026-02-24 19:02
VLAI
Title
Werkzeug safe_join() allows Windows special device names
Summary
Werkzeug is a comprehensive WSGI web application library. Versions 3.1.5 and below, the safe_join function allows Windows device names as filenames if preceded by other path segments. This was previously reported as GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact that safe_join accepts paths with multiple segments, such as example/NUL. The function 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 fixed in version 3.1.6.
Severity
6.3 (Medium)
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
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-02-24 19:02 UTC
CWE
  • CWE-67 - Improper Handling of Windows Device Names
Assigner
References
Impacted products
Vendor Product Version CPE status
pallets werkzeug Affected: < 3.1.6
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

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