The VGA module in QEMU improperly performs bounds checking on banked access to video memory, which allows local guest OS administrators to execute arbitrary code on the host by changing access modes after setting the bank register, aka the "Dark Port

Integer overflow in the VGA module in QEMU allows local guest OS users to cause a denial of service (out-of-bounds read and QEMU process crash) by editing VGA registers in VBE mode. CWE-190: Integer Overflow or Wraparound