An issue has been discovered in GitLab affecting all versions before 15.9.6, all versions starting from 15.10 before 15.10.5, all versions starting from 15.11 before 15.11.1. Under certain conditions, an attacker may be able to map a private email of a GitLab user to their GitLab account on an instance.
https://hackerone.com/reports/1794713
https://gitlab.com/gitlab-org/gitlab/-/issues/385246
https://gitlab.com/gitlab-org/cves/-/blob/master/2022/CVE-2022-4376.json