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[ CVE-2026-101918 · Published 28 Sep 2026 ]

PyJWT: Unauthenticated RecursionError DoS in pre-verification payload parse (PyJWKClient.get_signing_key_from_jwt / verify_signature=False)

CVSS 7.5 EPSS <1%1 agency advisoryFix available

[ Why it matters ]Priority signals

  • Public proof-of-concept exploit exists (CISA SSVC)

[ Description ]Official description

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.

[ Fixes ]Fixes and patches

  • PyJWT 2.15.0Fixed version · GitHub Advisories · pip package PyJWT: upgrade to 2.15.0 or later (affected >= 2.0.0a1, <= 2.14.0)
  • Patch on github.comVendor patch or bulletin · NVD · Reference tagged 'Patch' by NVD

[ Advisories ]Government CERT advisories

  • CERT-FRCERTFR-2026-AVI-1249

    Multiple vulnerabilities in VMware products Translated from French

    Multiple vulnerabilities have been discovered in VMware products. They allow an attacker to cause a security problem not specified by the vendor.

    CVE-2026-75595CVE-2026-53910CVE-2026-56404+288 more CVEs

[ Packages ]Affected open-source packages

[ References ]References