An issue was discovered in GitLab Enterprise Edition 11.x and 12.x before 12.0.9, 12.1.x before 12.1.9, and 12.2.x before 12.2.5. It has Incorrect Access Control.
https://about.gitlab.com/2019/09/10/critical-security-release-gitlab-12-dot-2-dot-5-released/