USN-3680-1

Ken Johnson and Jann Horn independently discovered that microprocessors utilizing speculative execution of a memory read may allow unauthorized memory reads via sidechannel attacks. An attacker in the guest could use this to expose sensitive guest information, including kernel memory. This update allows libvirt to expose new CPU features added by microcode updates to guests. (CVE-2018-3639)

Daniel P. Berrange discovered that libvirt incorrectly handled the QEMU guest agent. An attacker could possibly use this issue to consume resources, leading to a denial of service. (CVE-2018-1064)