In GitLab before 13.0.12, 13.1.6 and 13.2.3, it is possible to bypass E-mail verification which is required for OAuth Flow.
https://hackerone.com/reports/922456
https://gitlab.com/gitlab-org/gitlab/-/issues/228629
https://gitlab.com/gitlab-org/cves/-/blob/master/2020/CVE-2020-13292.json