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.

References

• https://nvd.nist.gov/vuln/detail/CVE-2021-21666
• https://www.jenkins.io/security/advisory/2021-06-10/#SECURITY-2367
• http://www.openwall.com/lists/oss-security/2021/06/10/14
• jenkinsci/kiuwan-plugin@a5f6fdb