An issue has been discovered in GitLab CE/EE affecting all versions starting from 12.6 before 14.3.6, all versions starting from 14.4 before 14.4.4, all versions starting from 14.5 before 14.5.2. GitLab was vulnerable to HTML Injection through the Swagger UI feature.
https://hackerone.com/reports/1133656
https://gitlab.com/gitlab-org/gitlab/-/issues/325901
https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-39910.json