CVE-2026-102266
criticalPyJWT is a Python implementation of JSON Web Token standards.
Vendor / product: Pyjwt Project — pyjwt
PyJWT 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.
CVSS
9.1
9.1 (CVSS v3.1)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N Severity source: NVD CVSS v3.1 (nvd@nist.gov)
Timeline (UTC)
Published: 2026-09-28 21:17
Modified: 2026-10-07 20:55
NVD status: Analyzed
Last synced 2 days ago
Verified against the source API 2026-10-27 07:07 UTC
Exploitation
Not listed in CISA KEV (as of last catalog sync)
Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).
Affected products
pyjwt_project / pyjwt 2.13.0
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
References
- https://github.com/jpadilla/pyjwt/commit/f91ed44dd65baaf457f4b3353ed35e98a753934c security-advisories@github.com
- https://github.com/jpadilla/pyjwt/releases/tag/2.14.0 security-advisories@github.com
- https://github.com/jpadilla/pyjwt/security/advisories/GHSA-9j54-fg26-wv3r security-advisories@github.com
- https://github.com/jpadilla/pyjwt/security/advisories/GHSA-9j54-fg26-wv3r 134c704f-9b21-4f2e-91b3-4a467353bcc0
Data sources
NVD CVE API 2.0 — fetched 2026-10-27 07:07 UTC · record ↗