CVE-2026-102266
PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.from_jw…
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.
- Vendor
- pyjwt project
- Product
- pyjwt
- CVSS 3.1
- 9.1 (critical), scored by NVD (primary)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- CVSS 3.1
- 7.4 (high), scored by security-advisories@github.comCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
- CWE
- CWE-347
- Published
- 2026-09-28
- NVD modified
- 2026-10-07
- NVD status
- Analyzed
Not in the CISA KEV catalogue at the last update.
EPSS
0.18% chance of exploitation in the next 30 days (percentile 7th)
FIRST EPSS, updated 17 Oct 2026. About EPSS
CVSS is severity, EPSS is likelihood, KEV means already exploited. EPSS is a statistical probability, not a certainty: a low score does not make a bug safe, and a high one does not prove it is being exploited.
References
- github.com (Patch)
- github.com (Product, Release Notes)
Data last updated 18 Oct 2026. Sources: NVD API 2.0, FIRST EPSS. Links: NVD, CISA KEV. Metadata only. ThreatWire does not host exploit code.