Several security issues were fixed in QEMU.
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. (CVE-2015-3214)
28 July 2015
A security issue affects these releases of Ubuntu and its derivatives:
Several security issues were fixed in QEMU.
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. (CVE-2015-3214)
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. (CVE-2015-5154)
Zhu Donghai discovered that QEMU incorrectly handled the SCSI driver. 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. This issue only affected Ubuntu 15.04. (CVE-2015-5158)
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
After a standard system update you need to restart all QEMU virtual machines to make all the necessary changes.