CVE-2026-48526highCWE-287CWE-347

CVE-2026-48526: high-severity vulnerability in jpadilla pyjwt

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

Published · Updated

Follow this CVE+ Monitor pyjwt+ Monitor pyjwt

E-mail alert when it lands in KEV, gets a public PoC or its score goes up.

21Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 7.4epss 0.4%
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.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Affected products
jpadilla · pyjwt
Related CVEs — jpadilla pyjwt

In the same product, most dangerous first.

CVE-2022-29217HIGHKey confusion through non-blocklisted public key formats in PyJWTEPSS 1.4%CVE-2024-53861LOWIssuer field partial matches allowed in pyjwtEPSS 0.8%CVE-2026-102274MEDIUMPyJWT: Malformed RSA JWK aborts parsing of an entire JWK SetEPSS 0.5%CVE-2026-101917MEDIUMPyJWT: PyJWKClient still amplifies unauthenticated JWKS fetches on unknown kid values (incomplete fix of CVE-2026-48524)EPSS 0.4%CVE-2026-101918MEDIUMPyJWT: Unauthenticated RecursionError DoS in pre-verification payload parse (PyJWKClient.get_signing_key_from_jwt / verify_signature=False)EPSS 0.4%CVE-2026-48524LOWPyJWT: PyJWKClient unbounded JWKS endpoint requests via attacker-controlled kid values (DoS)EPSS 0.4%