Mantis Bug Tracker (MantisBT) is an open source issue tracker. In versions prior to 2.25.6, due to insufficient access-level checks, any logged-in user allowed to perform Group Actions can access to the _Summary_ field of private Issues (i.e. having Private view status, or belonging to a private Project) via a crafted `bug_arr[]` parameter in *bug_actiongroup_ext.php*. This issue is fixed in version 2.25.6. There are no workarounds.
https://www.mantisbt.org/bugs/view.php?id=31086
https://github.com/mantisbt/mantisbt/security/advisories/GHSA-hf4x-6h87-hm79