An issue has been discovered in GitLab CE/EE affecting all versions starting from 8.11 before 14.3.6, all versions starting from 14.4 before 14.4.4, all versions starting from 14.5 before 14.5.2. Under specific condition an unauthorised project member was allowed to delete a protected branches due to a business logic error.
https://hackerone.com/reports/1318379
https://gitlab.com/gitlab-org/gitlab/-/issues/340445
https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-39931.json