Gber

**Name of the Vulnerable Software and Affected Versions** LightDM GTK+ Greeter versions prior to 1.7.1 **Description** The issue arises from the `start authentication` function in `lightdm-gtk-greeter.c`, which fails to handle the return value from the `lightdm greeter get authentication user` function correctly. This allows local users to cause a denial of service, specifically a NULL pointer dereference, by providing an empty `username`. **Recommendations** For versions prior to 1.7.1, update to version 1.7.1 or later to resolve the issue. As a temporary workaround, consider validating user input to prevent empty usernames from being processed by the `start authentication` function.