CVE-2026-21860: pallets werkzeug

Vulnerability summary

CVE-2026-21860 is a medium (CVSS 6.3) vulnerability in pallets werkzeug. EPSS estimates a 0.47% chance of exploitation in the next 30 days, higher than 39.6% of scored vulnerabilities.

Timeline

1. 08-01-2026
   PublishedVulnerability first disclosed.
2. 08-01-2026
   Last modifiedVulnerability information updated.

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.

• CWE-67Improper Handling of Windows Device NamesThe product constructs pathnames from user input, but it does not handle or incorrectly handles a pathname containing a Windows device name such as AUX or CON. This typically leads to denial of service or an information exposure when the application attempts to process the pathname as a regular file.