Jenkins Gitlab Hook Plugin 1.4.2 and earlier are vulnerable to Reflected cross-site scripting(XSS) so it does not escape project names in the build_now endpoint It allows remote attackers to inject arbitrary web script or HTML to the webpage.
Recommendations
Update Jenkins Gitlab Hook plugin to the latest version
Automated human-like penetration testing for your web apps & APIs
Teams using Beagle Security are set up in minutes, embrace release-based CI/CD security testing and save up to 65% with timely remediation of vulnerabilities. Sign up for a free account to see what it can do for you.