GitLab has remediated an issue in GitLab CE/EE affecting all versions from 12.0 before 18.10.8, 18.11 before 18.11.5, and 19.0 before 19.0.2 that under certain conditions could have allowed an authenticated user to access confidential issue details due to incorrect authorization checks.
Upgrade to versions 18.10.8, 18.11.5, 19.0.2 or above.