CVE-2026-28490
low-risk
Published 2026-03-16
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.
Do I need to act?
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0.01% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
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Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
6
CVSS 6.5/10
Medium
NETWORK
/ HIGH complexity
Affected Products (1)
Authlib
Affected Vendors
25
/ 100
low-risk
Severity
20/34 · Moderate
Exploitability
0/34 · Minimal
Exposure
5/34 · Minimal