Improper Handling of Windows Device Names Affecting werkzeug package, versions [,3.1.9)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-WERKZEUG-20305246
- published30 Sept 2026
- disclosed29 Sept 2026
- creditUnknown
Introduced: 29 Sep 2026
NewCVE-2026-102598 (opens in a new tab)How to fix?
Upgrade werkzeug to version 3.1.9 or higher.
Overview
Affected versions of this package are vulnerable to Improper Handling of Windows Device Names via safe_join on Windows, which fails to block special Windows device names (e.g. CON, NUL, AUX) when an empty Alternate Data Stream (ADS) marker (:) is appended to the name. An attacker can supply a path component such as CON: that bypasses the device-name check, causing the application to crash when the path is accessed on an NTFS filesystem.
Note: This is only exploitable on Windows hosts running on NTFS.