#VU124063 Use of a broken or risky cryptographic algorithm in authlib - CVE-2026-28490
Published: March 17, 2026
Vulnerability identifier: #VU124063
Vulnerability risk: High
CVSSv4.0: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Amber
CVE-ID: CVE-2026-28490
CWE-ID: CWE-327
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerable software:
authlib
authlib
Software vendor:
Authlib
Authlib
Description
The vulnerability allows a remote attacker to decrypt JWT tokens.
The vulnerability exists due to the JSON Web Encryption (JWE) implementation uses the RSA1_5 key management algorithm without requiring explicit opt-in and actively destroys the constant-time Bleichenbacher mitigation that the underlying cryptography library implements correctly. A remote attacker can decrypt JWT tokens used for authentication successful bypass authentication mechanisms use by OAuth and OpenID Connect servers.
Remediation
Install updates from vendor's website.