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MEDIUM severity

CVE-2021-21666 — kiuwanJenkinsPlugin

MEDIUMFix: jenkinsci/kiuwan-plugin@a5f6fdb

CVE-2021-21666 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in org.jenkins-ci.plugins:kiuwanJenkinsPlugin. A fix is available for org.jenkins-ci.plugins:kiuwanJenkinsPlugin — see the affected versions and patch details below.

Cross-site scripting in Jenkins Kiuwan Plugin

Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 12, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs68th percentile — riskier than 68% of all scored CVEsHighest risk
0.00%0.57%1.14%1.72%0.2%1.2%Apr 26Aug 26Oct 26

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

How urgent is this, really

CVE-2021-21666 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,987 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
☕org.jenkins-ci.plugins:kiuwanJenkinsPlugin

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 Kiuwan Plugin 1.6.0 and earlier does not escape query parameters in an error message for a form validation endpoint, resulting in a reflected cross-site scripting (XSS) vulnerability.

Only older releases of Jenkins are affected by this vulnerability. Jenkins 2.275 and newer, LTS 2.263.2 and newer include a protection preventing this from being exploitable.

Jenkins Kiuwan Plugin 1.6.1 escapes affected parts of the error message in the form validation endpoint.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.jenkins-ci.plugins:kiuwanJenkinsPluginall versions1.6.1org.jenkins-ci.plugins:kiuwanJenkinsPlugin:1.6.1

Affected Products

1 product · 1 configurations
Application
kiuwanjenkins
≤ 1.6.0
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:kiuwanJenkinsPlugin, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update org.jenkins-ci.plugins:kiuwanJenkinsPlugin to 1.6.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21666 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.

Frequently Asked Questions

Jenkins Kiuwan Plugin 1.6.0 and earlier does not escape query parameters in an error message for a form validation endpoint, resulting in a reflected cross-site scripting (XSS) vulnerability. Only older releases of Jenkins are affected by this vulnerability. Jenkins 2.275 and newer, LTS 2.263.2 and newer include a protection preventing this from being exploitable. Jenkins Kiuwan Plugin 1.6.1 escapes affected parts of the error message in the form validation endpoint.
O3 Security · Impact-Aware SCA

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CVE-2021-21666: kiuwanJenkinsPlugin XSS — Fixed in 1.6.1