Buffer overflow in the usb_host_handle_control function in the USB passthrough handling implementation in usb-linux.c in QEMU before 0.11.1 allows guest OS users to cause a denial of service (guest OS crash or hang) or possibly execute arbitrary code on the host OS via a crafted USB packet.
Multiple use-after-free vulnerabilities in vnc.c in the VNC server in QEMU 0.10.6 and earlier might allow guest OS users to execute arbitrary code on the host OS by establishing a connection from a VNC client and then (1) disconnecting during data transfer, (2) sending a message using incorrect integer data types, or (3) using the Fuzzy Screen Mode protocol, related to double free vulnerabilities.