Authentication bypass via unsigned JWE payload acceptance
Published Mar 4, 2026 · Updated Mar 4, 2026
Authentication bypass in pac4j-jwt before 4.5.9, 5.7.9, or 6.3.3 allows remote attackers to forge tokens through encrypted JWTs. JwtAuthenticator accepts a decrypted PlainJWT when toSignedJWT returns null, skips its signature-verification block, and creates a profile from unverified claims. Exploitation requires RSA-based JWE processing, the server's public key, and attacker-selected claims, granting authentication as any represented user or role.
Summary
What happened
Authentication bypass in pac4j-jwt before 4.5.9, 5.7.9, or 6.3.3 allows remote attackers to forge tokens through encrypted JWTs. JwtAuthenticator accepts a decrypted PlainJWT when toSignedJWT returns null, skips its signature-verification block, and creates a profile from unverified claims. Exploitation requires RSA-based JWE processing, the server's public key, and attacker-selected claims, granting authentication as any represented user or role.
The record
- CVE
- CVE-2026-29000
- Published
- Mar 4, 2026
- Updated
- Mar 4, 2026
- Vendor
- pac4j
- Product
- pac4j-jwt
- Classifications
- CWE-347, T1606
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 4, 2026CVE publishedPublication date reported by the CVE source.
- Mar 4, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=4.0 <4.5.9
- Affected versionversion=5.0 <5.7.9
- Affected versionversion=6.0 <6.3.3
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- CodeAnt pac4j-jwt JWE PlainJWT proof of conceptproof of concept · demonstrated
- kernelzeroday CVE-2026-29000 exploit repositoryproof of concept · demonstrated
- PtechAmanja pac4j-jwt authentication-bypass proof of conceptproof of concept · unverified
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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