A vulnerability was discovered in GitLab versions before 13.1.10, 13.2.8 and 13.3.4. Wiki was vulnerable to a parser attack that prohibits anyone from accessing the Wiki functionality through the user interface.
https://gitlab.com/gitlab-org/gitlab/-/issues/224496
https://gitlab.com/gitlab-org/gitlab/-/issues/208682
https://gitlab.com/gitlab-org/cves/-/blob/master/2020/CVE-2020-13311.json