Yesterday the developers of Ruby on Rails released a security advisory for file existence disclosure vulnerability CVE-2014-7818. GitLab is not affected by this vulnerability.
Background
CVE-2014-7818 affects Rails applications which have the config.serve_static_assets = true setting.
GitLab is shipped with config.serve_static_assets set to false in config/environments/production.rb because it lets NGINX (or Apache) serve static files.
Please contact us at support.gitlab.comif you have any questions about this issue.