GNOME Display Manager (gdm) before 3.18.2 allows physically proximate attackers to bypass the lock screen by holding the Escape key.

Silicon Integrated Systems WindowsXP Display Manager (aka VGA Driver Manager and VGA Display Manager) 6.14.10.3930 allows local users to gain privileges via a crafted (1) 0x96002400 or (2) 0x96002404 IOCTL call.

The default keybindings for wwm in LTSP Display Manager (ldm) 2.2.x before 2.2.7 allow remote attackers to execute arbitrary commands via the KP_RETURN keybinding, which launches a terminal window.

GNOME Display Manager (gdm) 3.4.1 and earlier, when disable-user-list is set to true, allows local users to cause a denial of service (unable to login) by pressing the cancel button after entering a user name.

X.Org xdm 1.1.10, 1.1.11, and possibly other versions, when performing authentication using certain implementations of the crypt API function that can return NULL, allows remote attackers to cause a denial of service (NULL pointer dereference and crash) by attempting to log into an account whose password field contains invalid characters, as demonstrated using the crypt function from glibc 2.17 and later with (1) the "!" character in the salt portion of a password field or (2) a password that has been encrypted using DES or MD5 in FIPS-140 mode.

GNOME Display Manager (gdm) before 2.21.1 allows local users to change permissions of arbitrary directories via a symlink attack on /tmp/.X11-unix/.

vicious-extensions/ve-misc.c in GNOME Display Manager (gdm) 2.20.x before 2.20.11, when GDM debug is enabled, logs the user password when it contains invalid UTF8 encoded characters, which might allow local users to gain privileges by reading the information from syslog logs.