MantisBT Missing Authorization access check in bug_actiongroup.php

An issue was discovered in MantisBT before 2.24.4. A missing access check in bug_actiongroup.php allows an attacker (with rights to create new issues) to use the COPY group action to create a clone, including all bugnotes and attachments, of any private issue (i.e., one having Private view status, or belonging to a private Project) via the bug_arr[] parameter. This provides full access to potentially confidential information.