The Ubuntu Date and Time Indicator (aka indicator-datetime) 13.10.0+13.10.x before 13.10.0+13.10.20131023.2-0ubuntu1.1 does not properly restrict access to Evolution, which allows local users to bypass the greeter screen restrictions by clicking the date.
https://bugs.launchpad.net/ubuntu/%2Bsource/indicator-datetime/%2Bbug/1246812
http://www.ubuntu.com/usn/USN-2186-1
http://www.openwall.com/lists/oss-security/2014/04/30/1
http://www.openwall.com/lists/oss-security/2014/04/29/3
http://bazaar.launchpad.net/~indicator-applet-developers/indicator-datetime/trunk.13.10/revision/282