GitLab Community and Enterprise Editions before 10.1.6, 10.2.6, and 10.3.4 are vulnerable to an authorization bypass issue in the Projects::MergeRequests::CreationsController component resulting in an attacker to see every project name and their respective namespace on a GitLab instance.
https://www.debian.org/security/2018/dsa-4206
https://hackerone.com/reports/301336
https://about.gitlab.com/2018/01/16/gitlab-10-dot-3-dot-4-released/