CVE-2026-28490 HIGH

CVE-2026-28490: Authlib Vulnerable to JWE RSA1_5 Bleichenbacher Padding Oracle

Vendor Authlib
Product authlib
Weakness CWE-203
Published March 16, 2026
Last update March 16, 2026
View on NVD All CVEs

CVSS base score

8.3/10
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Confidentiality —
Integrity —

CVSS vector

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

March 16, 2026 CVE published
March 16, 2026 Record updated