All versions of GitLab CE/EE starting from 12.8 before 13.10.5, all versions starting from 13.11 before 13.11.5, and all versions starting from 13.12 before 13.12.2 were affected by an issue in the handling of x509 certificates that could be used to spoof author of signed commits.
When requests to the internal network for webhooks are enabled, a server-side request forgery vulnerability in GitLab CE/EE affecting all versions starting from 10.5 was possible to exploit for an unauthenticated attacker even on a GitLab instance where registration is limited
An issue has been discovered in GitLab CE/EE affecting all previous versions. If the victim is an admin, it was possible to issue a CSRF in System hooks through the API.