CVE-2026-102272
As a result, public JWK bypasses asymmetric-key detection and becomes the HMAC secret.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.22%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.prepare_key in jwt/algorithms.py is affected because raw-JWK detector does not normalize accepted Unicode byte-order marks before checking for JSON. This occurs when a public JWK is prefixed with a UTF-8 BOM and used in a mixed-algorithm verification path. As a result, public JWK bypasses asymmetric-key detection and becomes the HMAC secret. Consequently, an attacker who knows the public key can forge authenticated tokens. This issue is fixed in version 2.14.0.
- CVSS 3.1
- 7.4 HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
- EPSS
- 0.22% probability · 12th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-347
- Affected
- pyjwt project/pyjwt
- Source
- security-advisories@github.com
EPSS moved from 0.2% on 29 September 2026 to 0.2% on 26 October 2026.
References
- https://github.com/jpadilla/pyjwt/commit/180783930de91876bc0d601f826a1f2956057291Patch
- https://github.com/jpadilla/pyjwt/releases/tag/2.14.0Product, Release Notes
- https://github.com/jpadilla/pyjwt/security/advisories/GHSA-r6x4-923q-g947Exploit, Mitigation, Vendor Advisory
- https://github.com/jpadilla/pyjwt/security/advisories/GHSA-r6x4-923q-g947Exploit, Mitigation, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.