CVE-2026-29000
CVE-2026-29000 is a critical-severity vulnerability with a CVSS 3.x base score of 9.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-347.
Key facts
- Severity: Critical (CVSS 3.x base score 9.1)
- CVSS v4: 9.3
- EPSS exploit prediction: 6% (92nd percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-9505
- Weakness: CWE-347
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2026-29000?
- 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.
- How severe is CVE-2026-29000?
- CVE-2026-29000 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
- Is CVE-2026-29000 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (92nd percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-29000?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- Does CVE-2026-29000 have an EU (EUVD) identifier?
- Yes. CVE-2026-29000 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-9505.
- When was CVE-2026-29000 published?
- CVE-2026-29000 was published on 2026-03-04 and last updated on 2026-06-17.
References
- https://www.codeant.ai/security-research/pac4j-jwt-authentication-bypass-public-key
- https://www.pac4j.org/blog/security-advisory-pac4j-jwt-jwtauthenticator.html
- https://www.vulncheck.com/advisories/pac4j-jwt-jwtauthenticator-authentication-bypass
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