PyJWT accepts unknown `crit` header extensions (RFC 7515 §4.1.11 MUST violation)
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5epss 0.3%
exploitation probability
0.3%top 81% of all CVEs
observed exploitation
nono source reports it
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Affected products
jpadilla · pyjwtReferences
https://access.redhat.com/errata/RHSA-2026:10140https://access.redhat.com/errata/RHSA-2026:10141https://access.redhat.com/errata/RHSA-2026:10184https://access.redhat.com/errata/RHSA-2026:12176https://access.redhat.com/errata/RHSA-2026:13508https://access.redhat.com/errata/RHSA-2026:13512https://access.redhat.com/errata/RHSA-2026:13545https://access.redhat.com/errata/RHSA-2026:13553https://access.redhat.com/errata/RHSA-2026:13672https://access.redhat.com/errata/RHSA-2026:13916https://access.redhat.com/errata/RHSA-2026:17083https://access.redhat.com/errata/RHSA-2026:19138