CVE-2026-102598 · GHSA-g6x2-hccm-hh4m
Werkzeug safe_join() allows Windows special device names
- Risk score
- 49/100
- CVSS
- 6.3 v4.0
- Exploit chance (30 days)
- 0.4%
- Published
- 29 Sep 2026
Open in the live forecast Today's forecast
What to know
- What it is
- Werkzeug is a comprehensive WSGI web application library. Prior to 3.1.9, the safe_join function used by send_from_directory can allow a NUL: special-device path because safe_join checks the Windows device name without first removing an empty NTFS ADS marker. The trigger is that an application runs on Windows with NTF…
- Affected
- Werkzeug (pip) < 3.1.9
- Fix
- Upgrade Werkzeug to 3.1.9 or later.
- Exploitation
- No known exploitation
Why it is Yellow
- CVSS 6.3 medium
- On your watchlist: PyPI
Affected packages
| Package | Ecosystem | Vulnerable | Fixed in |
|---|---|---|---|
| Werkzeug | pip | < 3.1.9 | 3.1.9 |
References
- https://github.com/advisories/GHSA-g6x2-hccm-hh4m
- https://github.com/pallets/werkzeug/security/advisories/GHSA-g6x2-hccm-hh4m
- https://nvd.nist.gov/vuln/detail/CVE-2026-102598
- https://github.com/pallets/werkzeug/pull/3309
- https://github.com/pallets/werkzeug/commit/8d77320bcdf3a34941ec06dcf16b03c065cd21b6
- https://github.com/pallets/werkzeug/releases/tag/3.1.9
- https://github.com/advisories/GHSA-g6x2-hccm-hh4m
Original description
Werkzeug is a comprehensive WSGI web application library. Prior to 3.1.9, the safe_join function used by send_from_directory can allow a NUL: special-device path because safe_join checks the Windows device name without first removing an empty NTFS ADS marker. The trigger is that an application runs on Windows with NTFS and serves a user-specified path ending in a special device name such as NUL:. The attack mechanism is that a requested path ends in a Windows special device name with an empty ADS marker. The impact is that the special device opens successfully and the file read hangs indefinitely. This issue is fixed in version 3.1.9.
Last activity 29 Sep 2026. Patch Forecast updates every hour.