GitLab EE, versions 8.3 up to 11.x before 11.3.11, 11.4 before 11.4.8, and 11.5 before 11.5.1, is vulnerable to an insecure object reference vulnerability that allows a Guest user to set the weight of an issue they create.
https://gitlab.com/gitlab-org/gitlab-ee/issues/7696
https://about.gitlab.com/2018/11/28/security-release-gitlab-11-dot-5-dot-1-released/