An issue was discovered in GitLab CE/EE affecting all versions starting from 8.14 prior to 17.1.7, starting from 17.2 prior to 17.2.5, and starting from 17.3 prior to 17.3.2, which allows an attacker to trigger a pipeline as an arbitrary user under certain circumstances.
https://securityaffairs.com/168375/security/gitlab-ce-ee-critical-issue.html