In GitLab EE 11.3 through 12.5.3, 12.4.5, and 12.3.8, insufficient parameter sanitization for the Maven package registry could lead to privilege escalation and remote code execution vulnerabilities under certain conditions.
https://about.gitlab.com/blog/categories/releases/
https://about.gitlab.com/blog/2019/12/10/critical-security-release-gitlab-12-5-4-released/