Description
PyJWT is a JSON Web Token implementation in Python. Prior to 2.12.0, PyJWT does not validate the crit (Critical) Header Parameter defined in RFC 7515 §4.1.11. When a JWS token contains a crit array listing extensions that PyJWT does not understand, the library accepts the token instead of rejecting it. This violates the MUST requirement in the RFC. This vulnerability is fixed in 2.12.0.
Affected products
pyjwt_project: pyjwt
References10
- github.com/jpadilla/pyjwt/security/advisories/GHSA-752w-5fwx-jx… ExploitMitigationVendor Advisory
- github.com/jpadilla/pyjwt/security/advisories/GHSA-752w-5fwx-jx… ExploitMitigationVendor Advisory
- lists.debian.org/debian-lts-announce/2026/05/msg00008.html
- access.redhat.com/errata/RHSA-2026:10140
- access.redhat.com/errata/RHSA-2026:10141
- access.redhat.com/errata/RHSA-2026:10184
- access.redhat.com/errata/RHSA-2026:12176
- access.redhat.com/errata/RHSA-2026:13508
- access.redhat.com/errata/RHSA-2026:13512
- access.redhat.com/errata/RHSA-2026:13545
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - EPSS — exploit probability
- 0% percentile: 23 · as of 12 November 2026
- CWE
- CWE-345CWE-863CWE-347
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