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 has Incorrect Access Control (issue 1 of 3). The contents of an LFS object can be accessed by an unauthorized user, if the file size and OID are known.
https://gitlab.com/gitlab-org/gitlab-workhorse/issues/197
https://about.gitlab.com/2019/01/31/security-release-gitlab-11-dot-7-dot-3-released/