The SOAP API in MantisBT before 1.2.9 does not properly enforce the bugnote_allow_user_edit_delete and delete_bug_threshold permissions, which allows remote authenticated users with read and write SOAP API privileges to delete arbitrary bug reports and bug notes.
bug_actiongroup.php in MantisBT before 1.2.9 does not properly check the report_bug_threshold permission of the receiving project when moving a bug report, which allows remote authenticated users with the report_bug_threshold and move_bug_threshold privileges for a project to bypass intended access restrictions and move bug reports to a different project.