See how lightdm gtk\+ greeter project compares to other vendors in security performance
The startauthentication function in lightdm-gtk-greeter.c in LightDM GTK+ Greeter before 1.7.1 does not properly handle the return value from the lightdmgreetergetauthenticationuser function, which allows local users to cause a denial of service (NULL pointer dereference) via an empty username.