CVE-2026-102266

NameCVE-2026-102266
DescriptionPyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.from_jwk is affected because PyJWK verification path used the decoded key without applying prepare_key validation. This occurs when a trusted JWK Set contains an oct entry with an empty k value. As a result, an attacker signs an HMAC token with the same zero-length key accepted by PyJWT. Consequently, forged token can carry arbitrary authenticated claims. This issue is fixed in version 2.14.0.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
pyjwt (PTS)bookworm, bookworm (security)2.6.0-1+deb12u1vulnerable
trixie (security), trixie2.10.1-2+deb13u1vulnerable
forky2.13.0-1vulnerable
sid2.15.1-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
pyjwtsource(unstable)2.14.0-1

Notes

https://github.com/jpadilla/pyjwt/security/advisories/GHSA-9j54-fg26-wv3r
Fixed by: https://github.com/jpadilla/pyjwt/commit/f91ed44dd65baaf457f4b3353ed35e98a753934c (2.14.0)

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