An issue was discovered in GitLab Community and Enterprise Edition 8.9 through 11.11. Wiki Pages contained a lack of input validation which resulted in a persistent XSS vulnerability.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2019-4053
https://about.gitlab.com/releases/2019/06/03/security-release-gitlab-11-dot-11-dot-1-released/