Junglewise Threat Intelligence

CVE-2026-28490: PYSEC-2026-2116 - Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.9, a cryptographic padding oracle vulnerabil

CVE-2026-28490 · Severity: medium · CVSS 4 · Published 2026-03-16

Technologies: authlib (PyPI). Vendors: PyPI.

Executive brief

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.9, a cryptographic padding oracle vulnerability was identified in the Authlib Python library concerning the implementation of the JSON Web Encryption (JWE) RSA1_5 key management algorithm. Authlib registers RSA1_5 in its default algorithm registry without requiring explicit opt-in, and actively destroys the constant-time Bleichenbacher mitigation that the underlying cryptography library implements correctly. This issue has been patched in version 1.6.9.

Affected products

  • PyPI authlib

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