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Advisory record · GHSA-g6x2-hccm-hh4m

Werkzeug safe_join() allows Windows special device names

CVSS 6.3 MediumEPSS 0.0037 · 31st percentile

Published by the GitHub Advisory Database at 5 Oct 2026, 23:48 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
werkzeugPyPI<3.1.93.1.9
Identifiers
GHSA-g6x2-hccm-hh4m · CVE-2026-102598 · PYSEC-2026-4312
Weakness (CWE)
CWE-67
Tags
Published
5 Oct 2026
Updated
15 Oct 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Werkzeug versions before 3.1.9 have a flaw in safe_join() that lets Windows device names through when they carry an empty ADS marker, such as NUL:. An attacker who can request files through an application's send_from_directory on Windows with NTFS can make reads hang indefinitely. Upgrade to Werkzeug 3.1.9 or later.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
6.3 Medium 4.0 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 CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0037, the 31st percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:08 UTC First seen by agentprime
  2. 31 Oct 2026, 14:08 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.