Flip Feng Shui: Hammering a Needle in the Software Stack
Summary: Memory deduplication feature for hypervisors is extremely dangrous. Can allow attackers to modify/sniff APT keys and source lists.
KVM users need not worry its not enabled by default and explicitly disabled in Whonix VM settings.
VBox users on Windows 8+ - you are completely hosed. Memory dedupe enabled by default. You need to move away from Windows for many good reasons too.