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CVE-2026-29000

Severity9.3 Critical CVSS 4.0 2 scores
Fixed in6.3.3, 5.7.9, 4.5.9
WeaknessCWE-347
Published4 Mar 2026
Updated8 Oct 2026

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.

Exploitation status

Proof of concept only

A proof of concept exists, but no reviewed exploit catalogue lists this CVE.

  • CISA KEV not listed
  • VulnCheck KEV not listed
  • CISA Vulnrichment exploitation: poc CISA recorded that an exploit has been demonstrated. Automatable: yes, technical impact: total.
  • Indexed PoC 19 indexed Published artifacts you can open, in GitHub PoC; first seen 2026-03-05.
  • EPSS 6.2% chance in 30 days

9 of these are GitHub repositories with fewer than 5 stars. They are listed for reference and don't count toward the exploitation status above.

IndexArtifactStarsFirst seen
GitHub PoC pac4j-jwt JwtAuthenticator auth bypass (CVE-2026-29000) writeup and PoCs 9 2026-03-05
GitHub PoC CVE-2026-29000 – pac4j-jwt Authentication Bypass (CVSS 10.0). One-click admin forge via public key JWE wrapping. Leaks configs, users, secrets. Keep-alive, proxy, custom JWKS. Educational PoC Exploit tool. 4 2026-05-12
GitHub PoC CVE-2026-29000 PoC: pac4j-jwt PlainJWT-in-JWE authentication bypass. 3 2026-05-03
GitHub PoC cve-2026-29000 exploit 2 2026-03-16
GitHub PoC alihussainzada/CVE-2026-29000-Python-PoC-pac4j-JWT-AuthenticationBypass-Poc 2 2026-03-13
GitHub PoC PoC and technical research for CVE-2026-29000. Exploring JWT authentication bypass, vulnerability analysis, and security testing. 1 2026-10-08
GitHub PoC CVE-2026-29000 - pac4j-jwt (< 4.5.9 / < 5.7.9 / < 6.3.3) JwtAuthenticator authentication bypass PoC 1 2026-07-11
GitHub PoC Python POC, Exploit for CVE-2026-29000 1 2026-05-30
GitHub PoC Proof-of-Concept (PoC) for an authentication bypass vulnerability affecting applications using pac4j-jwt with JWE (JSON Web Encryption). 1 2026-03-24
GitHub PoC otuva/CVE-2026-29000 1 2026-03-13

Waratek protection

Mitigation candidate

A kind of vulnerability Waratek's rules address, with exploit code published or exploitation reported. No rule exists and none is planned yet. The decision below says what we found to build a rule from.

  • Protection none
  • Action unverified
  • Review automated Inferred
  • Record active
Decided by The affected package being open source on Maven, so the fix can be read
Finding This CVE affects an open-source Java library published on Maven Central (Maven packages: org.pac4j:pac4j-jwt), so it is squarely in ARMR's territory and the source needed to understand the defect is public. That makes it a candidate for an ARMR patch rule. No rule exists and none is scheduled: the diff between the affected and fixed versions has not been read, and a closer look may find no hook point ARMR can act on.

CVSS

9.3 CRITICAL v4.0 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X 2 metrics

We show the highest score from the newest CVSS version. Scores from different versions can't be compared, and the first score listed is sometimes a 0.0 placeholder.

VersionScoreBandVectorAssignerType
CVSS 4.0 9.3 CRITICAL 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X disclosure@vulncheck.com Secondary published
CVSS 3.1 9.1 CRITICAL CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N disclosure@vulncheck.com Secondary

Affected software and releases

Maven packages

Affected and fixed versions, from OSV.dev
PackageIntroducedFixedLast affected
org.pac4j:pac4j-jwt 6.0.4.1 6.3.3 unbounded
org.pac4j:pac4j-jwt 5.0.0-RC1 5.7.9 unbounded
org.pac4j:pac4j-jwt 0 4.5.9 unbounded

Products and versions

1 product, 3 version entries
SourceVendorProductSchemeAffected versions
osv org.pac4j pac4j-jwt generic < 4.5.9 · ≥ 5.0.0 and < 5.7.9 · ≥ 6.0.4.1 and < 6.3.3

References

URLTags
https://github.com/pac4j/pac4j PACKAGE
https://www.codeant.ai/security-research/pac4j-jwt-authentication-bypass-public-key WEB
https://www.pac4j.org/blog/security-advisory-pac4j-jwt-jwtauthenticator.html WEB
https://www.vulncheck.com/advisories/pac4j-jwt-jwtauthenticator-authentication-bypass WEB

Timeline

Published2026-03-04By the CVE Program.
NVD record modified2026-10-08NVD's own last-modified date for this record.