CVE-2013-4459
LightDM 1.7.5 through 1.8.3 and 1.9.x before 1.9.2 does not apply the AppArmor profile to the Guest account, which allows local users to bypass intended restrictions by leveraging the Guest account.
Date published : 2013-11-23
https://bugs.launchpad.net/ubuntu/%2Bsource/lightdm/%2Bbug/1243339
http://lists.freedesktop.org/archives/lightdm/2013-October/000471.html