An issue has been discovered in GitLab CE/EE affecting all versions starting from 8.8.9. A specially crafted request could bypass Multipart protection and read files in certain specific paths on the server. Affected versions are: >=8.8.9, <13.3.9,>=13.4, <13.4.5,>=13.5, <13.5.2.
https://hackerone.com/reports/927953
https://gitlab.com/gitlab-org/gitlab/-/issues/230878
https://gitlab.com/gitlab-org/cves/-/blob/master/2020/CVE-2020-13356.json