An issue has been discovered in GitLab CE/EE affecting all versions starting from 8.7 before 15.10.8, all versions starting from 15.11 before 15.11.7, all versions starting from 16.0 before 16.0.2. A Regular Expression Denial of Service was possible via sending crafted payloads to the preview_markdown endpoint.
https://hackerone.com/reports/1947187
https://gitlab.com/gitlab-org/gitlab/-/issues/408273
https://gitlab.com/gitlab-org/cves/-/blob/master/2023/CVE-2023-2198.json