pac4j-jwt v<4.5.9/5.7.9/6.3.3 JWE Auth Bypass
CVE-2026-29000 Published on March 4, 2026
pac4j-jwt JwtAuthenticator Authentication Bypass
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.
Vulnerability Analysis
CVE-2026-29000 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. An automatable proof of concept (POC) exploit exists. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality and integrity, and no impact on availability.
Weakness Type
Improper Verification of Cryptographic Signature
The software does not verify, or incorrectly verifies, the cryptographic signature for data.
Products Associated with CVE-2026-29000
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Affected Versions
pac4j-jwt:- Version 4.0 and below 4.5.9 is affected.
- Version 5.0 and below 5.7.9 is affected.
- Version 6.0 and below 6.3.3 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.