Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
gdk/gdkwindow.c in GTK+ before 2.18.5, as used in gnome-screensaver before 2.28.1, performs implicit paints on windows of type GDK_WINDOW_FOREIGN, which triggers an X error in certain circumstances and consequently allows physically proximate attackers to bypass screen locking and access an unattended workstation by pressing the Enter key many times.
CWE-362 - Race Condition
A race condition occurs in a shared memory program when two threads/processes access the same shared memory data, and at least one thread executes a write operation. This vulnerability manipulates the time to check vs. time to use (TOC/TOU) gap between the threads in the critical section to cause disorientation in the shared data. The impact can vary from compromising the confidentiality of the system to causing the system to crash or to execute arbitrary code.