Medium 6.3Published Sep 29, 2026

CVE-2026-102598Werkzeug safe_join() allows Windows special device names

Updated under an hour ago (2026-10-19 08:30 UTC)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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.

CVSS: 6.3 MEDIUM (v4.0, CNA)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
Weakness (CWE): CWE-67
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Awaiting Analysis
Record last updated: Sep 29, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

pallets werkzeug pallets:werkzeug (from the name)	before 3.1.9	CNA record

References

https://github.com/pallets/werkzeug/security/advisories/GHSA-g6x2-hccm-hh4mx-refsource-confirm
https://github.com/pallets/werkzeug/pull/3309x-refsource-misc
https://github.com/pallets/werkzeug/commit/8d77320bcdf3a34941ec06dcf16b03c065cd21b6x-refsource-misc
https://github.com/pallets/werkzeug/releases/tag/3.1.9x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.