Xen, when used on a system providing PV backends, allows local guest OS administrators to cause a denial of service (host OS crash) or gain privileges by writing to memory shared between the frontend and backend, aka a double fetch vulnerability.
lists.opensuse.org/opensuse-security-announce/2016-03/msg00094.html
lists.opensuse.org/opensuse-security-announce/2016-04/msg00045.html
lists.opensuse.org/opensuse-security-announce/2016-07/msg00005.html
www.debian.org/security/2016/dsa-3434
www.debian.org/security/2016/dsa-3471
www.debian.org/security/2016/dsa-3519
www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.html
www.securityfocus.com/bid/79592
www.securitytracker.com/id/1034479
xenbits.xen.org/xsa/advisory-155.html
security.gentoo.org/glsa/201604-03