Description
PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, PyJWT HMACAlgorithm.prepare_key is affected because HMAC key guard only recognizes top-level public JWK forms and misses container representations. This occurs when an application allows HMAC and asymmetric algorithms and passes a public JWK container as the raw key. As a result, public asymmetric key material is accepted as the HMAC secret. Consequently, an attacker who knows the public key can forge a token with arbitrary authenticated claims. This issue is fixed in version 2.14.0.
Affected products
pyjwt_project: pyjwt
References3
- github.com/jpadilla/pyjwt/security/advisories/GHSA-w2cx-738m-mc… Vendor Advisory
- github.com/jpadilla/pyjwt/commit/801cd128528c62d9b23fcd161d1a2e… Patch
- github.com/jpadilla/pyjwt/releases/tag/2.14.0 ProductRelease Notes
Metrics
- CVSS 3.1
-
7.4
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N - EPSS — exploit probability
- 0% percentile: 7 · as of 9 November 2026
- CWE
- CWE-347
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.