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.
Scores
CVSS v3
7.5
EPSS
0.0001
EPSS Percentile
2.3%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
yes
Technical Impact
partial
Details
CWE
CWE-863
CWE-345
Status
published
Products (3)
jpadilla/pyjwt
< 2.12.0
pyjwt_project/pyjwt
< 2.12.0
pypi/PyJWT
0 - 2.12.0PyPI
Published
Mar 13, 2026
Tracked Since
Mar 14, 2026