The manager_invoke_notify_message function in systemd 231 and earlier allows local users to cause a denial of service (assertion failure and PID 1 hang) via a zero-length message received over a notify socket.
http://www.ubuntu.com/usn/USN-3094-1
http://www.securitytracker.com/id/1037320
http://www.securityfocus.com/bid/93223
http://www.openwall.com/lists/oss-security/2016/09/30/1
http://www.openwall.com/lists/oss-security/2016/09/28/9