A vulnerability was discovered in GitLab versions before 13.1.10, 13.2.8 and 13.3.4. A user without 2 factor authentication enabled could be prohibited from accessing GitLab by being invited into a project that had 2 factor authentication inheritance.
https://hackerone.com/reports/637675
https://gitlab.com/gitlab-org/gitlab/-/issues/29989
https://gitlab.com/gitlab-org/cves/-/blob/master/2020/CVE-2020-13308.json