CVE-2026-101918: medium-severity vulnerability in jpadilla pyjwt
PyJWT: Unauthenticated RecursionError DoS in pre-verification payload parse (PyJWKClient.get_signing_key_from_jwt / verify_signature=False)
Published · Updated
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.3epss 0.3%
exploitation probability
0.3%top 80% of all CVEs
observed exploitation
nono source reports it
PyJWT is a Python implementation of JSON Web Token standards. From 2.0.0a1 until 2.15.0, PyJWT PyJWKClient.get_signing_key_from_jwt is affected because payload parser catches ValueError but not RecursionError. This occurs when an attacker-controlled recursively nested payload reaches json.loads. As a result, documented PyJWT exception handling does not contain the failure. Consequently, an unauthenticated request can raise an exception that may produce an HTTP 500 response. The advisory-defined affected implementation also includes jwt/api_jwt.py, verify_signature=False. This issue is fixed in version 2.15.0.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Affected products
jpadilla · pyjwtRelated 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-2026-48526HIGHPyJWT: Public-key JWK accepted as HMAC secret enables forged HS256 tokens when mixed families are allowedEPSS 0.4%CVE-2026-48525MEDIUMPyJWT: Unauthenticated DoS via unbounded Base64URL decoding of unused payload segment in b64=false detached JWSEPSS 0.4%CVE-2026-102274MEDIUMPyJWT: Malformed RSA JWK aborts parsing of an entire JWK SetEPSS 0.4%CVE-2026-101917MEDIUMPyJWT: PyJWKClient still amplifies unauthenticated JWKS fetches on unknown kid values (incomplete fix of CVE-2026-48524)EPSS 0.4%