Ubuntu Security Notice 2692-1 – Matt Tait discovered that QEMU incorrectly handled PIT emulation. In a non-default configuration, a malicious guest could use this issue to cause a denial of service, or possibly execute arbitrary code on the host as the user running the QEMU process. In the default installation, when QEMU is used with libvirt, attackers would be isolated by the libvirt AppArmor profile. Kevin Wolf discovered that QEMU incorrectly handled processing ATAPI commands. A malicious guest could use this issue to cause a denial of service, or possibly execute arbitrary code on the host as the user running the QEMU process. In the default installation, when QEMU is used with libvirt, attackers would be isolated by the libvirt AppArmor profile. Various other issues were also addressed.