KVM (Kernel-based Virtual Machine) is a full virtualization solution for Linux on AMD64 and Intel 64 systems. The qemu-kvm package provides the user-space component for running virtual machines using KVM.
An information leak flaw was found in the way QEMU's RTL8139 emulation implementation processed network packets under RTL8139 controller's C+ mode of operation. An unprivileged guest user could use this flaw to read up to 65 KB of uninitialized QEMU heap memory. (CVE-2015-5165)
Red Hat would like to thank the Xen project for reporting this issue. Upstream acknowledges Donghai Zhu of Alibaba as the original reporter.
All qemu-kvm users are advised to upgrade to these updated packages, which contain a backported patch to correct this issue. After installing this update, shut down all running virtual machines. Once all virtual machines have shut down, start them again for this update to take effect.