GitLab has remediated an issue in GitLab CE/EE affecting all versions from 18.2 before 18.8.9, 18.9 before 18.9.5, and 18.10 before 18.10.3 that could have allowed an authenticated user with custom role permissions to demote or remove higher-privileged group members due to improper authorization checks on member management operations.
https://about.gitlab.com/releases/2026/04/08/patch-release-gitlab-18-10-3-released/