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.
rhn.redhat.com/errata/RHSA-2016-2610.html
rhn.redhat.com/errata/RHSA-2016-2694.html
www.openwall.com/lists/oss-security/2016/09/28/9
www.openwall.com/lists/oss-security/2016/09/30/1
www.securityfocus.com/bid/93223
www.securitytracker.com/id/1037320
www.ubuntu.com/usn/USN-3094-1
github.com/systemd/systemd/issues/4234
www.agwa.name/blog/post/how_to_crash_systemd_in_one_tweet