GitLab has remediated an issue in GitLab CE/EE affecting all versions from 15.0 before 19.3.6, 19.4 before 19.4.3, and 19.5 before 19.5.1 that, when a merge request in a public project referenced a confidential issue from a private project, an authenticated user with no project membership could have read the confidential issue's title, due to a viewer-independent fragment cache key that incorrectly shared per-user-redacted rendered content across all users.