CVE-2026-29000: pac4j-jwt Authentication Bypass Vulnerability

CRITICAL
Advisory Identifier: GHSA-pm7g-w2cf-q238
Share
CVSS 10.0
CWE-347
Published
Advisory Summary

CVE-2026-29000 is a CRITICAL (CVSS 10.0) authentication bypass vulnerability (CWE-347: Improper Verification of Cryptographic Signature) affecting pac4j-jwt libraries in the Maven ecosystem. The issue involves jwtauthenticator authentication bypass via jwe-wrapped plainjwt. Remediation is available by upgrading affected packages to version 6.3.3, 5.7.9, 4.5.9.

CVE-2026-29000 at a Glance

CVE Identifier CVE-2026-29000
GHSA Identifier GHSA-pm7g-w2cf-q238
Severity CRITICAL
CVSS v3.1 Base Score 10.0
CWE Classification CWE-347: Improper Verification of Cryptographic Signature
Affected Product pac4j-jwt
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 10.0

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Changed (S:C)
Confidentiality High (C:H)
Integrity High (I:H)
Availability Low (A:L)

How to Fix CVE-2026-29000

To remediate this vulnerability, upgrade all affected pac4j-jwt dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

org.pac4j:pac4j-jwt fixed: 6.3.3 
<dependency>
    <groupId>org.pac4j</groupId>
    <artifactId>pac4j-jwt</artifactId>
    <version>6.3.3</version>
</dependency>
org.pac4j:pac4j-jwt fixed: 5.7.9 
<dependency>
    <groupId>org.pac4j</groupId>
    <artifactId>pac4j-jwt</artifactId>
    <version>5.7.9</version>
</dependency>
org.pac4j:pac4j-jwt fixed: 4.5.9 
<dependency>
    <groupId>org.pac4j</groupId>
    <artifactId>pac4j-jwt</artifactId>
    <version>4.5.9</version>
</dependency>
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree -Dincludes=org.pac4j

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-29000, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=org.pac4j

Analyze the terminal output to locate any version of pac4j-jwt in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 6.3.3), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.pac4j command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-347: Improper Verification of Cryptographic Signature, where the product does not verify, or incorrectly verifies, the cryptographic signature for data. In pac4j-jwt, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

CVE-2026-29000 Affected pac4j-jwt Versions

3 component(s)
Fixed Versions:
6.3.35.7.94.5.9
Product / Package Ecosystem Affected Versions Fixed Version
org.pac4j:pac4j-jwt
maven/org.pac4j/pac4j-jwt
Maven
≥ 6.0.4.1
< 6.3.3
6.3.3
org.pac4j:pac4j-jwt
maven/org.pac4j/pac4j-jwt
Maven
≥ 5.0.0-RC1
< 5.7.9
5.7.9
org.pac4j:pac4j-jwt
maven/org.pac4j/pac4j-jwt
Maven
< 4.5.9
4.5.9

References

NVD — CVE-2026-29000 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-29000
pac4j-jwt Source Repository REPOSITORY
https://github.com/pac4j/pac4j
pac4j-jwt Security Information SECURITY
https://www.codeant.ai/security-research/pac4j-jwt-authentication-bypass-public-key
pac4j-jwt Security Information SECURITY
https://www.pac4j.org/blog/security-advisory-pac4j-jwt-jwtauthenticator.html
www.vulncheck.com/advisories/pac4j-jw... WEB
https://www.vulncheck.com/advisories/pac4j-jwt-jwtauthenticator-authentication-bypass

Frequently Asked Questions

What is CVE-2026-29000?
CVE-2026-29000 is a security vulnerability in pac4j-jwt involving JwtAuthenticator Authentication Bypass via JWE-Wrapped PlainJWT under CWE-347: Improper Verification of Cryptographic Signature.
Which pac4j-jwt versions are affected?
Affected versions include releases prior to 6.3.3, 5.7.9, 4.5.9 across affected packages: org.pac4j:pac4j-jwt.
What version fixes CVE-2026-29000?
Upgrading to 6.3.3, 5.7.9, 4.5.9 (or the latest patched release for your respective branch) resolves the vulnerability.
Is pac4j-jwt affected?
Yes, org.pac4j:pac4j-jwt is affected in releases prior to 6.3.3, 5.7.9, 4.5.9. Upgrade your dependency to 6.3.3, 5.7.9, 4.5.9 or later.
What is the CVSS score of CVE-2026-29000?
CVE-2026-29000 has a CVSS v3.1 base score of 10.0 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L.
What CWE is associated with CVE-2026-29000?
CVE-2026-29000 is classified under CWE-347: Improper Verification of Cryptographic Signature (The product does not verify, or incorrectly verifies, the cryptographic signature for data.).
How can I check Maven dependencies for CVE-2026-29000?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.pac4j'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-pm7g-w2cf-q238",
  "modified" : "2026-03-06T15:41:53Z",
  "published" : "2026-03-05T00:31:11Z",
  "aliases" : [ "CVE-2026-29000" ],
  "summary" : "pac4j-jwt: JwtAuthenticator Authentication Bypass via JWE-Wrapped PlainJWT",
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.pac4j:pac4j-jwt"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "6.0.4.1"
      }, {
        "fixed" : "6.3.3"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.pac4j:pac4j-jwt"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "5.0.0-RC1"
      }, {
        "fixed" : "5.7.9"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.pac4j:pac4j-jwt"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.5.9"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-29000"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/pac4j/pac4j"
  }, {
    "type" : "WEB",
    "url" : "https://www.codeant.ai/security-research/pac4j-jwt-authentication-bypass-public-key"
  }, {
    "type" : "WEB",
    "url" : "https://www.pac4j.org/blog/security-advisory-pac4j-jwt-jwtauthenticator.html"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/pac4j-jwt-jwtauthenticator-authentication-bypass"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-347" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-06T15:41:53Z",
    "nvd_published_at" : "2026-03-04T22:16:18Z"
  }
}