MantisBT before 1.2.12 does not use an expected default value during decisions about whether a user may modify the status of a bug, which allows remote authenticated users to bypass intended access restrictions and make status changes by leveraging a blank value for a per-status setting.
http://www.securityfocus.com/bid/56520
http://www.mantisbt.org/bugs/view.php?id=14496
http://www.mantisbt.org/bugs/changelog_page.php?version_id=150
http://openwall.com/lists/oss-security/2012/11/14/1
http://lists.fedoraproject.org/pipermail/package-announce/2012-November/093064.html
http://lists.fedoraproject.org/pipermail/package-announce/2012-November/093063.html
http://lists.fedoraproject.org/pipermail/package-announce/2012-November/092926.html