# CVE-2026-28490

## Summary

- **CVE ID:** CVE-2026-28490
- **Severity:** HIGH
- **CVSS Score:** 8.3 (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)
- **CWE:** CWE-203, CWE-327
- **Published:** Mar 16, 2026
- **Last Modified:** Mar 16, 2026

## Description

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

- authlib — authlib (< 1.6.9)

## References

- [CNA](https://github.com/authlib/authlib/security/advisories/GHSA-7432-952r-cw78)
- [CNA](https://github.com/authlib/authlib/commit/48b345f29f6c459f11c6a40162b6c0b742ef2e22)
- [CNA](https://github.com/authlib/authlib/releases/tag/v1.6.9)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.14%
- **EPSS Percentile:** 3.8

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._