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MEDIUM severity

CVE-2021-21623 — matrix-auth

MEDIUMFix: jenkinsci/matrix-auth-plugin@bbe3585

CVE-2021-21623 is a medium-severity (CVSS 6.5) CWE-863 vulnerability in org.jenkins-ci.plugins:matrix-auth. A fix is available for org.jenkins-ci.plugins:matrix-auth — see the affected versions and patch details below.

Incorrect permission checks in Jenkins Matrix Authorization Strategy Plugin may allow accessing some items

Also known asGHSA-96jw-3xw4-mq9p
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 3, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.0%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs63th percentile — riskier than 63% of all scored CVEsHighest risk
0.00%0.50%1.01%1.51%0.1%1.0%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
☕org.jenkins-ci.plugins:matrix-auth

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

Items (like jobs) can be organized hierarchically in Jenkins, using the Folders Plugin or something similar. An item is expected to be accessible only if all its ancestors are accessible as well.

Matrix Authorization Strategy Plugin 2.6.5 and earlier does not correctly perform permission checks to determine whether an item should be accessible.

This allows attackers with Item/Read permission on nested items to access them, even if they lack Item/Read permission for parent folders.\n\nMatrix Authorization Strategy Plugin 2.6.6 requires Item/Read permission on parent items to grant Item/Read permission on an individual item.

As a workaround in older releases, do not grant permissions on individual items to users who do not have access to parent items.

In case of problems, the Java system property hudson.security.AuthorizationMatrixProperty.checkParentPermissions can be set to false, completely disabling this fix.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.jenkins-ci.plugins:matrix-authall versions2.6.6org.jenkins-ci.plugins:matrix-auth:2.6.6

Affected Products

1 product · 1 configurations
Application
matrix authorization strategyjenkins
≤ 2.6.5
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.jenkins-ci.plugins:matrix-auth, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update org.jenkins-ci.plugins:matrix-auth to 2.6.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21623 is resolved across your whole dependency graph.

  3. Workarounds

    Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate
ProductFixed inAdvisory
Red Hat OpenShift Container Platform 4.8jenkins-0:2.289.1.1624020353-1.el8RHSA-2021:2437

Frequently Asked Questions

Items (like jobs) can be organized hierarchically in Jenkins, using the Folders Plugin or something similar. An item is expected to be accessible only if all its ancestors are accessible as well. Matrix Authorization Strategy Plugin 2.6.5 and earlier does not correctly perform permission checks to determine whether an item should be accessible. This allows attackers with Item/Read permission on nested items to access them, even if they lack Item/Read permission for parent folders.\n\nMatrix Authorization Strategy Plugin 2.6.6 requires Item/Read permission on parent items to grant Item/Read p
O3 Security · Impact-Aware SCA

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CVE-2021-21623: matrix-auth — Fixed in 2.6.6