An issue has been discovered in GitLab CE/EE affecting all versions starting from 10.5 before 14.3.6, all versions starting from 14.4 before 14.4.4, all versions starting from 14.5 before 14.5.2. Unauthorized external users could perform Server Side Requests via the CI Lint API
https://hackerone.com/reports/1236965
https://gitlab.com/gitlab-org/gitlab/-/issues/346187
https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-39935.json