An issue has been discovered in GitLab CE/EE affecting all versions starting with version 8.10. It was possible to trigger a timeout on a page with markdown by using a specific amount of block-quotes.
{ "cpes": [ "cpe:2.3:a:gitlab:gitlab:*:*:*:*:community:*:*:*", "cpe:2.3:a:gitlab:gitlab:*:*:*:*:enterprise:*:*:*", "cpe:2.3:a:gitlab:gitlab:*:*:*:*:*:*:*:*" ], "severity": "Medium" }