In all versions of GitLab CE/EE since version 13.0, a privileged user, through an API call, can change the visibility level of a group or a project to a restricted option even after the instance administrator sets that visibility option as restricted in settings.
A regular expression denial of service issue in GitLab versions 8.13 to 14.2.5, 14.3.0 to 14.3.3 and 14.4.0 could cause excessive usage of resources when a specially crafted username was used when provisioning a new user