The smartcard interaction in SPICE allows remote attackers to cause a denial of service (QEMU-KVM process crash) or possibly execute arbitrary code via vectors related to connecting to a guest VM, which triggers a heap-based buffer overflow.
lists.opensuse.org/opensuse-updates/2016-07/msg00003.html
lists.opensuse.org/opensuse-updates/2016-07/msg00004.html
www.debian.org/security/2016/dsa-3596
www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html
www.ubuntu.com/usn/USN-3014-1
access.redhat.com/errata/RHSA-2016:1204
access.redhat.com/errata/RHSA-2016:1205
security.gentoo.org/glsa/201606-05