Buffer overflow in the virtio subsystem in qemu-kvm 0.14.0 and earlier allows privileged guest users to cause a denial of service (guest crash) or gain privileges via a crafted indirect descriptor related to "virtqueue in and out requests."

The pciej_write function in hw/acpi_piix4.c in the PIIX4 Power Management emulation in qemu-kvm does not check if a device is hotpluggable before unplugging the PCI-ISA bridge, which allows privileged guest users to cause a denial of service (guest crash) and possibly execute arbitrary code by sending a crafted value to the 0xae08 (PCI_EJ_BASE) I/O port, which leads to a use-after-free related to "active qemu timers."

qemu-kvm before 0.11.0 disables VNC authentication when the password is cleared, which allows remote attackers to bypass authentication and establish VNC sessions.