CVE-2026-28490

Summary

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 Software

VendorProductVersion RangeStatus
authlibauthlib< 1.6.9affected

Weaknesses

  • CWE-203: CWE-203: Observable Discrepancy
  • CWE-327: CWE-327: Use of a Broken or Risky Cryptographic Algorithm

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: poc
    • Automatable: no
    • Technical Impact: partial

References