Is werkzeug affected by CVE-2025-66221?

PyPI werkzeug is affected in <3.1.4.

Is CVE-2025-66221 being exploited?

Not on the CISA KEV list. EPSS exploit probability is 0.5%.

medium

CVE-2025-66221

Q: Is CVE-2025-66221 being exploited?

Not on the CISA KEV list. EPSS exploit probability is 0.5%.

PyPI · werkzeug

Summary

Werkzeug safe_join() allows Windows special device names

Severity: medium
EPSS: 0.5% (p37)
Also known as: GHSA-hgf8-39gv-g3f2
Published: 2025-12-02

References

https://github.com/pallets/werkzeug/security/advisories/GHSA-hgf8-39gv-g3f2
https://nvd.nist.gov/vuln/detail/CVE-2025-66221
https://github.com/pallets/werkzeug/commit/4b833376a45c323a189cd11d2362bcffdb1c0c13

Related advisories

CVE-2026-27199 — medium · PyPI/werkzeug
CVE-2026-21860 — 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.