An issue was discovered in GitLab CE/EE affecting all versions prior to 16.11.6, starting from 17.0 prior to 17.0.4, and starting from 17.1 prior to 17.1.2, which allows a subdomain takeover in GitLab Pages.
https://hackerone.com/reports/2523654
https://gitlab.com/gitlab-org/gitlab/-/issues/464558
https://about.gitlab.com/releases/2024/07/10/patch-release-gitlab-17-1-2-released/