CVE-2026-42521: matrix Insecure Deserialization — Fix

Description

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, allowing 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.

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CVSS v3.1 Score

6.5

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

EPSS — Exploit Prediction

0.0007

Probability of exploitation

0.22%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-502 Deserialization of Untrusted Data

Affected Products

Vendor	Product	Versions
jenkins	matrix_authorization_strategy	2.1 — 3.2.10
jenkins	matrix_authorization_strategy	All
jenkins	matrix_authorization_strategy	All
jenkins	matrix_authorization_strategy	All

References

Advisories & Patches

https://www.jenkins.io/security/advisory/2026-04-29/#SECURITY-3676

Frequently Asked Questions

What is CVE-2026-42521? +

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, allowing 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. It has a CVSS v3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2026-42521? +

CVE-2026-42521 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0007, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-42521? +

CVE-2026-42521 affects products from jenkins, specifically: matrix_authorization_strategy. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-42521? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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