D-Bus 1.4.x through 1.6.x before 1.6.30, 1.8.x before 1.8.16, and 1.9.x before 1.9.10 does not validate the source of ActivationFailure signals, which allows local users to cause a denial of service (activation failure error returned) by leveraging a race condition involving sending an ActivationFailure signal before systemd responds.
http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html
http://www.openwall.com/lists/oss-security/2015/02/09/6
http://www.mandriva.com/security/advisories?name=MDVSA-2015:176
http://www.debian.org/security/2015/dsa-3161
http://lists.opensuse.org/opensuse-updates/2015-02/msg00066.html