An issue was discovered in GitLab Community and Enterprise Edition before 11.5.8, 11.6.x before 11.6.6, and 11.7.x before 11.7.1. It allows Information Disclosure (issue 3 of 6). For installations using GitHub or Bitbucket OAuth integrations, it is possible to use a covert redirect to obtain the user OAuth token for those services.
https://gitlab.com/gitlab-org/gitlab-ce/issues/56663
https://about.gitlab.com/2019/01/31/security-release-gitlab-11-dot-7-dot-3-released/