The VGA module in QEMU improperly performs bounds checking on banked access to video memory, which allows local guest OS administrators to execute arbitrary code on the host by changing access modes after setting the bank register, aka the "Dark Portal" issue.
https://lists.gnu.org/archive/html/qemu-devel/2016-05/msg01197.html
https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05164862
https://access.redhat.com/errata/RHSA-2016:1224
http://xenbits.xen.org/xsa/advisory-179.html
http://www.ubuntu.com/usn/USN-2974-1
http://www.securitytracker.com/id/1035794
http://www.securityfocus.com/bid/90316
http://www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.html
http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2016-3090545.html
http://www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html
http://www.openwall.com/lists/oss-security/2016/05/09/3
http://www.debian.org/security/2016/dsa-3573
http://support.citrix.com/article/CTX212736
http://rhn.redhat.com/errata/RHSA-2016-1943.html
http://rhn.redhat.com/errata/RHSA-2016-1019.html
http://rhn.redhat.com/errata/RHSA-2016-1002.html
http://rhn.redhat.com/errata/RHSA-2016-1001.html
http://rhn.redhat.com/errata/RHSA-2016-1000.html
http://rhn.redhat.com/errata/RHSA-2016-0999.html
http://rhn.redhat.com/errata/RHSA-2016-0997.html