CVE-2026-29000 CRITICAL

CVE-2026-29000: pac4j-jwt JwtAuthenticator Authentication Bypass

Vendor Pac4J
Product pac4j-jwt
Weakness CWE-347
Published March 4, 2026
Last update May 11, 2026

CVSS base score

9.3/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

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

What the vulnerability does

01Description

pac4j-jwt versions prior to 4.5.9, 5.7.9, and 6.3.3 contain an authentication bypass vulnerability in JwtAuthenticator when processing encrypted JWTs that allows remote attackers to forge authentication tokens. Attackers who possess the server's RSA public key can create a JWE-wrapped PlainJWT with arbitrary subject and role claims, bypassing signature verification to authenticate as any user including administrators.

Key dates

02Disclosure timeline

March 4, 2026 CVE published
May 11, 2026 Record updated