CVE-2026-29000: CWE-347 Improper Verification of Cryptographic Signature in pac4j pac4j-jwt
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.
AI Analysis
Technical Summary
CVE-2026-29000 is an authentication bypass vulnerability in pac4j-jwt's JwtAuthenticator component affecting versions prior to 4.5.9, 5.7.9, and 6.3.3. The vulnerability arises from improper verification of cryptographic signatures (CWE-347) when processing encrypted JWTs. Attackers possessing the server's RSA public key can craft JWE-wrapped PlainJWT tokens with arbitrary subject and role claims, bypassing signature verification and gaining unauthorized authentication as any user, including administrators. This vulnerability has a CVSS 4.0 score of 9.3, indicating critical severity.
Potential Impact
Successful exploitation allows remote attackers to bypass authentication controls by forging JWT tokens, potentially gaining unauthorized access with any user privileges, including administrative rights. This compromises the authentication mechanism and can lead to full system compromise depending on the application context.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict access to the server's RSA public key and monitor for suspicious JWT usage. Avoid using affected versions and upgrade to versions 4.5.9, 5.7.9, or 6.3.3 or later once confirmed by the vendor.
CVE-2026-29000: CWE-347 Improper Verification of Cryptographic Signature in pac4j pac4j-jwt
Description
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.
CVSS v4.0
Score 9.3critical
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-29000 is an authentication bypass vulnerability in pac4j-jwt's JwtAuthenticator component affecting versions prior to 4.5.9, 5.7.9, and 6.3.3. The vulnerability arises from improper verification of cryptographic signatures (CWE-347) when processing encrypted JWTs. Attackers possessing the server's RSA public key can craft JWE-wrapped PlainJWT tokens with arbitrary subject and role claims, bypassing signature verification and gaining unauthorized authentication as any user, including administrators. This vulnerability has a CVSS 4.0 score of 9.3, indicating critical severity.
Potential Impact
Successful exploitation allows remote attackers to bypass authentication controls by forging JWT tokens, potentially gaining unauthorized access with any user privileges, including administrative rights. This compromises the authentication mechanism and can lead to full system compromise depending on the application context.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict access to the server's RSA public key and monitor for suspicious JWT usage. Avoid using affected versions and upgrade to versions 4.5.9, 5.7.9, or 6.3.3 or later once confirmed by the vendor.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-03-03T16:42:01.012Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 69a8ac26d1a09e29cb796104
Added to database: 03/04/2026, 22:03:18 UTC
Last enriched: 07/15/2026, 10:49:57 UTC
Last updated: 07/27/2026, 20:52:03 UTC
Views: 3110
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