Format string vulnerability in the host chooser window (gdmchooser) in GNOME Foundation Display Manager (gdm) allows local users to execute arbitrary code via format string specifiers in a hostname, which are used in an error dialog.
The GDM daemon in GNOME Display Manager (GDM) before 2.14.13, 2.16.x before 2.16.7, 2.18.x before 2.18.4, and 2.19.x before 2.19.5 does not properly handle NULL return values from the gstrsplit function, which allows local users to cause a denial of service (persistent daemon crash) via a crafted command to the daemon's socket, related to (1) gdm.c and (2) gdmconfig.c in daemon/, and (3) gdmconfig.c and (4) gdmflexiserver.c in gui/.