An issue has been discovered in GitLab affecting all versions starting from 12.9 before 16.0.8, all versions starting from 16.1 before 16.1.3, all versions starting from 16.2 before 16.2.2. It was possible to leak a user's email via an error message for groups that restrict membership by email domain.
Credits
Thanks [shells3c](https://hackerone.com/shells3c) for reporting this vulnerability through our HackerOne bug bounty program
