An issue has been discovered in GitLab affecting all versions starting from 12.1. Incorrect headers in specific project page allows attacker to have a temporary read access to the private repository
https://hackerone.com/reports/1043480
https://gitlab.com/gitlab-org/gitlab/-/issues/289944
https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-22167.json