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MEDIUM severity

Stored XSS vulnerability in Jenkins button labelsGHSA-wv63-gwr9-5c55

MEDIUMFix: jenkinsci/jenkins@8c451b0

GHSA-wv63-gwr9-5c55 is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in org.jenkins-ci.main:jenkins-core. A fix is available for org.jenkins-ci.main:jenkins-core — see the affected versions and patch details below.

Also known asBIT-jenkins-2021-21608CVE-2021-21608
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Nov 10, 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 CVEs64th percentile — riskier than 64% of all scored CVEsHighest risk
0.00%0.51%1.03%1.54%0.5%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

2 pkgs affected
☕org.jenkins-ci.main:jenkins-core☕org.jenkins-ci.main:jenkins-core

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

Jenkins 2.274 and earlier, LTS 2.263.1 and earlier does not escape button labels in the Jenkins UI.

This results in a cross-site scripting vulnerability exploitable by attackers with the ability to control button labels. An example of buttons with a user-controlled label are the buttons of the Pipeline input step.

Jenkins 2.275, LTS 2.263.2 escapes button labels in the Jenkins UI.

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.jenkins-ci.main:jenkins-coreall versions2.275org.jenkins-ci.main:jenkins-core:2.275
☕Mavenorg.jenkins-ci.main:jenkins-core≥ 2.263.2&&< 2.2752.275org.jenkins-ci.main:jenkins-core:2.275

Affected Products

1 product · 2 configurations
Application
jenkinsjenkins
≤ 2.274
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.main:jenkins-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update org.jenkins-ci.main:jenkins-core to 2.275 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wv63-gwr9-5c55 is resolved across your whole dependency graph.

  3. Workarounds

    Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

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 HatImportant
ProductFixed inAdvisory
Red Hat OpenShift Container Platform 3.11jenkins-0:2.263.3.1612433584-1.el7RHSA-2021:0637
Red Hat OpenShift Container Platform 4.5conmon-2:2.0.21-1.rhaos4.5.el7RHSA-2021:0429
Red Hat OpenShift Container Platform 4.6jenkins-0:2.263.3.1612434510-1.el8RHSA-2021:0423
Red Hat OpenShift Container Platform 4.8atomic-openshift-service-idler-0:4.8.0-202106281541.p0.git.39cfc66.assembly.stream.el8RHSA-2021:2437

Frequently Asked Questions

Jenkins 2.274 and earlier, LTS 2.263.1 and earlier does not escape button labels in the Jenkins UI. This results in a cross-site scripting vulnerability exploitable by attackers with the ability to control button labels. An example of buttons with a user-controlled label are the buttons of the Pipeline `input` step. Jenkins 2.275, LTS 2.263.2 escapes button labels in the Jenkins UI.
O3 Security · Impact-Aware SCA

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Stored XSS vulnerability in Jenkins button labels