CVE-2026-42521: Matrix auth Unsafe Deserialization Allows Invocation Of Vulnerability

MODERATE
Advisory Identifier: GHSA-jp9r-mmhw-vff3
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CVSS 6.5
CWE-502
Published
Advisory Summary

CVE-2026-42521 is a MODERATE (CVSS 6.5) unsafe deserialization allows invocation of vulnerability (CWE-502: Deserialization of Untrusted Data) affecting Matrix auth libraries in the Maven ecosystem. The issue involves unsafe deserialization allows invocation of parameterless constructors. Remediation is available by upgrading affected packages to version 3.2.10.

CVE-2026-42521 at a Glance

CVE Identifier CVE-2026-42521
GHSA Identifier GHSA-jp9r-mmhw-vff3
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-502: Deserialization of Untrusted Data
Affected Product Matrix auth
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 6.5

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

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

How to Fix CVE-2026-42521

To remediate this vulnerability, upgrade all affected Matrix auth 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.jenkins-ci.plugins:matrix-auth fixed: 3.2.10 
<dependency>
    <groupId>org.jenkins-ci.plugins</groupId>
    <artifactId>matrix-auth</artifactId>
    <version>3.2.10</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.jenkins-ci.plugins

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-42521, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=org.jenkins-ci.plugins

Analyze the terminal output to locate any version of Matrix auth in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.2.10), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.jenkins-ci.plugins 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-502: Deserialization of Untrusted Data, where the product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid. In Matrix auth, 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

Jenkins Matrix Authorization Strategy Plugin 2.0-beta-1 through 3.2.9 (both inclusive) invokes parameterless constructors of classes specified in configuration when deserializing inheritance strategies, without restricting the classes that can be instantiated. This can be abused by attackers with Item/Configure permission to instantiate arbitrary types, which may lead to information disclosure or other impacts depending on the classes available on the classpath. Matrix Authorization Strategy Plugin 3.2.10 verifies that the class being instantiated is an inheritance strategy implementation, preventing instantiation of arbitrary types.

CVE-2026-42521 Affected Matrix auth Versions

1 component(s)
Fixed Versions:
3.2.10
Product / Package Ecosystem Affected Versions Fixed Version
org.jenkins-ci.plugins:matrix-auth
maven/org.jenkins-ci.plugins/matrix-auth
Maven
≥ 2.0-beta-1
< 3.2.10
3.2.10

References

NVD — CVE-2026-42521 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-42521
Matrix auth Source Repository REPOSITORY
https://github.com/jenkinsci/matrix-auth-plugin
Matrix auth Security Information SECURITY
https://www.jenkins.io/security/advisory/2026-04-29/#SECURITY-3676

Frequently Asked Questions

What is CVE-2026-42521?
CVE-2026-42521 is a security vulnerability in Matrix auth involving Unsafe deserialization allows invocation of parameterless constructors under CWE-502: Deserialization of Untrusted Data.
Which Matrix auth versions are affected?
Affected versions include releases prior to 3.2.10 across affected packages: org.jenkins-ci.plugins:matrix-auth.
What version fixes CVE-2026-42521?
Upgrading to 3.2.10 (or the latest patched release for your respective branch) resolves the vulnerability.
Is matrix-auth affected?
Yes, org.jenkins-ci.plugins:matrix-auth is affected in releases prior to 3.2.10. Upgrade your dependency to 3.2.10 or later.
What is the CVSS score of CVE-2026-42521?
CVE-2026-42521 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N.
What CWE is associated with CVE-2026-42521?
CVE-2026-42521 is classified under CWE-502: Deserialization of Untrusted Data (The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.).
How can I check Maven dependencies for CVE-2026-42521?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.jenkins-ci.plugins'. 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-jp9r-mmhw-vff3",
  "modified" : "2026-05-06T22:47:11Z",
  "published" : "2026-04-29T15:30:38Z",
  "aliases" : [ "CVE-2026-42521" ],
  "summary" : "Jenkins Matrix Authorization Strategy Plugin: Unsafe deserialization allows invocation of parameterless constructors",
  "details" : "Jenkins Matrix Authorization Strategy Plugin 2.0-beta-1 through 3.2.9 (both inclusive) invokes parameterless constructors of classes specified in configuration when deserializing inheritance strategies, without restricting the classes that can be instantiated.\n\nThis can be abused by attackers with Item/Configure permission to instantiate arbitrary types, which may lead to information disclosure or other impacts depending on the classes available on the classpath.\n\nMatrix Authorization Strategy Plugin 3.2.10 verifies that the class being instantiated is an inheritance strategy implementation, preventing instantiation of arbitrary types.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.jenkins-ci.plugins:matrix-auth"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.0-beta-1"
      }, {
        "fixed" : "3.2.10"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 3.2.9"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-42521"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/jenkinsci/matrix-auth-plugin"
  }, {
    "type" : "WEB",
    "url" : "https://www.jenkins.io/security/advisory/2026-04-29/#SECURITY-3676"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-502" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-06T22:47:11Z",
    "nvd_published_at" : "2026-04-29T14:16:19Z"
  }
}