An issue has been discovered in GitLab CE/EE affecting all versions starting from 14.3 before 14.9.5, all versions starting from 14.10 before 14.10.4, all versions starting from 15.0 before 15.0.1. It may be possible for malicious group maintainers to add new members to a project within their group, through the REST API, even after their group owner enabled a setting to prevent members from being added to projects within that group.