MantisBT has an authorization bypass in private issue monitoring

Using a crafted POST request to bug_monitor_add.php, a user with project-level access can add themselves as a monitor for a private issue they do not have access to. Despite displaying an Access Denied error, the application accepts the request and creates a monitor relationship for the private issue.

Impact

Direct access to the private issue remains blocked, but the user will receive email notifications for updates, leading to disclosure of the private issue's metadata and content.

Patches

• 0a93267deba445fb9d15250c16e6fdb1246ffa65

Workarounds

None

Credits

Thanks to Vishal Shukla for discovering and responsibly reporting the issue.