The dbus-daemon in D-Bus 1.2.x through 1.4.x, 1.6.x before 1.6.20, and 1.8.x before 1.8.4, sends an AccessDenied error to the service instead of a client when the client is prohibited from accessing the service, which allows local users to cause a denial of service (initialization failure and exit) or possibly conduct a side-channel attack via a D-Bus message to an inactive service.
https://bugs.freedesktop.org/show_bug.cgi?id=78979
http://www.securityfocus.com/bid/67986
http://www.mandriva.com/security/advisories?name=MDVSA-2015:176
http://www.debian.org/security/2014/dsa-2971
http://secunia.com/advisories/59798
http://secunia.com/advisories/59611
http://secunia.com/advisories/59428
http://seclists.org/oss-sec/2014/q2/509
http://lists.opensuse.org/opensuse-updates/2014-09/msg00049.html
http://lists.opensuse.org/opensuse-updates/2014-07/msg00012.html
http://lists.opensuse.org/opensuse-updates/2014-06/msg00042.html
http://cgit.freedesktop.org/dbus/dbus/commit/?h=dbus-1.8&id=24c590703ca47eb71ddef453de43126b90954567