CVE-2025-66221: medium-severity vulnerability in pallets werkzeug
Werkzeug safe_join() allows Windows special device names
Published · Updated
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13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 6.3epss 0.5%
Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.4, Werkzeug's safe_join 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. 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 patched in version 3.1.4.
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
Affected products
pallets · werkzeugRelated CVEs — pallets werkzeug
In the same product, most dangerous first.
CVE-2024-34069HIGHWerkzeug's improper usage of a pathname and improper CSRF protection results in the remote command executionEPSS 3.4%CVE-2023-25577HIGHWerkzeug may allow high resource usage when parsing multipart form data with many fieldsEPSS 1.4%CVE-2023-46136HIGHWerkzeug vulnerable to high resource usage when parsing multipart/form-data containing a large part with CR/LF character at the beginningEPSS 1.3%CVE-2024-49767MEDIUMWerkzeug possible resource exhaustion when parsing file data in formsEPSS 1.1%CVE-2024-49766MEDIUMWerkzeug safe_join not safe on WindowsEPSS 0.8%CVE-2026-27199MEDIUMWerkzeug safe_join() allows Windows special device namesEPSS 0.6%