systemd does not properly use D-Bus for communication with a polkit authority, which allows local users to bypass intended access restrictions by leveraging a PolkitUnixProcess PolkitSubject race condition via a (1) setuid process or (2) pkexec process, a related issue to CVE-2013-4288.
https://bugzilla.redhat.com/show_bug.cgi?id=1006680
http://www.ubuntu.com/usn/USN-1961-1