The Palinopsia Bug
Is your VirtualBox reading your E-Mail? Reconstruction of FrameBuffers from VRAM
This document describes a method of reading and displaying previously used framebuffers from a variety of popular graphics cards. In all 4 tested laptops the content of the VRAM was not erased upon reboot. It is also possible to show that the content of the host VRAM can be accessed from a VirtualBox guest, thereby leaking possibly confidential information from a trusted host into an untrusted guest machine.
via The Palinopsia Bug.