An issue has been discovered in GitLab affecting all versions starting with 13.3. GitLab was vulnerable to a stored XSS by using the design feature in issues.
https://hackerone.com/reports/1212067
https://gitlab.com/gitlab-org/gitlab/-/issues/332420
https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-22238.json