An issue was discovered in GitLab Community and Enterprise Edition 12.0 through 12.2.1. An IDOR in the epic notes API that could result in disclosure of private milestones, labels, and other information.
https://gitlab.com/gitlab-org/gitlab-ee/issues/11431
https://about.gitlab.com/2019/08/29/security-release-gitlab-12-dot-2-dot-3-released/