CVE-2026-48526

HIGH

PyJWT: Public-key JWK accepted as HMAC secret enables forged HS256 tokens when mixed families are allowed

Title source: cna
STIX 2.1

Description

PyJWT is a JSON Web Token implementation in Python. Prior to 2.13.0, when the verifier is decoding JSON Web Tokens, while supporting both asymmetric and HMAC algorithms, the library does not validate use of JSON Web Keys in HMAC algorithm, allowing attacker to use the issuer public key as the secret key for HMAC algorithm. This vulnerability is fixed in 2.13.0.

References (32)

Core 32
Core References

Scores

CVSS v3 7.4
EPSS 0.0040
EPSS Percentile 32.3%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

CISA SSVC

Vulnrichment
Exploitation poc
Automatable no
Technical Impact total

Details

CWE
CWE-287 CWE-347
Status published
Products (3)
jpadilla/pyjwt < 2.13.0
pyjwt_project/pyjwt < 2.13.0
pypi/pyjwt 0 - 2.13.0PyPI
Published May 28, 2026
Tracked Since May 28, 2026