Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
The org.pac4j:pac4j-jwt package, versions before 4.5.9, 5.7.9, and 6.3.3 (and 5.0.0-RC1 onward through 5.7.8, and 6.0.4.1 onward through 6.3.2), contains an authentication bypass in JwtAuthenticator when it processes encrypted JWTs. A remote attacker who has the server's RSA public key can build an encrypted unsigned token with arbitrary subject and role claims and authenticate as any user, including administrators. Upgrade to 4.5.9, 5.7.9, 6.3.3, or a later release in the same line.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 9.3 | Critical | 4.0 | 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 | CNA (VulnCheck) |
- CISA KEV Not listed.
- EPSS 0.062, the 93rd percentile, on 11 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 14:21 UTC First seen by agentprime
- 31 Oct 2026, 14:21 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-pm7g-w2cf-q238
- OSV: GHSA-pm7g-w2cf-q238
- nvd.nist.gov/vuln/detail/CVE-2026-29000
- github.com/pac4j/pac4j
- www.codeant.ai/security-research/pac4j-jwt-authentication-bypass-public-key
- www.pac4j.org/blog/security-advisory-pac4j-jwt-jwtauthenticator.html
- www.vulncheck.com/advisories/pac4j-jwt-jwtauthenticator-authentication-bypass