CVE-2026-28490
MEDIUMAuthlib Vulnerable to JWE RSA1_5 Bleichenbacher Padding Oracle
Title source: cnaDescription
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.
References (3)
Scores
CVSS v3
6.5
EPSS
0.0001
EPSS Percentile
3.4%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
no
Technical Impact
partial
Details
CWE
CWE-327
CWE-203
Status
published
Products (2)
authlib/authlib
< 1.6.9 (2 CPE variants)
pypi/authlib
0 - 1.6.9PyPI
Published
Mar 16, 2026
Tracked Since
Mar 16, 2026