Is werkzeug affected by CVE-2026-21860?

PyPI werkzeug is affected in <3.1.5.

Is CVE-2026-21860 being exploited?

Not on the CISA KEV list. EPSS exploit probability is 0.4%.

medium

CVE-2026-21860

Q: Is CVE-2026-21860 being exploited?

Not on the CISA KEV list. EPSS exploit probability is 0.4%.

PyPI · werkzeug

Summary

Werkzeug safe_join() allows Windows special device names with compound extensions

Severity: medium
EPSS: 0.4% (p34)
Also known as: GHSA-87hc-h4r5-73f7
Published: 2026-01-08

References

https://github.com/pallets/werkzeug/security/advisories/GHSA-87hc-h4r5-73f7
https://nvd.nist.gov/vuln/detail/CVE-2026-21860
https://github.com/pallets/werkzeug/commit/7ae1d254e04a0c33e241ac1cca4783ce6c875ca3

Related advisories

CVE-2026-27199 — medium · PyPI/werkzeug
CVE-2025-66221 — medium · PyPI/werkzeug

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Sources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.