It was found that the x86 ISA (Instruction Set Architecture) is prone to a denial of service attack inside a virtualized environment in the form of an infinite loop in the microcode due to the way (sequential) delivering of benign exceptions such as #AC (alignment check exception) is handled. A privileged user inside a guest could use this flaw to create denial of service conditions on the host kernel.
http://www.openwall.com/lists/oss-security/2015/11/10/6
https://bugzilla.redhat.com/show_bug.cgi?id=1277172
https://github.com/torvalds/linux/commit/54a20552e1eae07aa240fa370a0293e006b5faed
http://xenbits.xen.org/xsa/advisory-156.html
http://www.oracle.com/technetwork/topics/security/cpujan2016-2367955.html
http://www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.html
http://www.oracle.com/technetwork/topics/security/linuxbulletinjan2016-2867209.html
http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html
http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00038.html
http://www.securityfocus.com/bid/77528
http://rhn.redhat.com/errata/RHSA-2016-0046.html
http://lists.opensuse.org/opensuse-security-announce/2016-02/msg00013.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-November/172435.html
http://lists.opensuse.org/opensuse-security-announce/2015-11/msg00035.html
http://www.ubuntu.com/usn/USN-2805-1
http://www.debian.org/security/2015/dsa-3396
http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00005.html
http://www.ubuntu.com/usn/USN-2802-1
http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00026.html
http://www.securitytracker.com/id/1034105
http://www.debian.org/security/2016/dsa-3454
http://rhn.redhat.com/errata/RHSA-2015-2636.html
http://support.citrix.com/article/CTX202583
http://lists.opensuse.org/opensuse-updates/2015-12/msg00039.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-November/172300.html
http://www.debian.org/security/2015/dsa-3414
http://www.ubuntu.com/usn/USN-2801-1
http://www.ubuntu.com/usn/USN-2804-1
http://lists.fedoraproject.org/pipermail/package-announce/2015-November/172187.html
http://www.ubuntu.com/usn/USN-2807-1
http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00031.html
http://www.ubuntu.com/usn/USN-2806-1
http://www.ubuntu.com/usn/USN-2800-1
http://lists.opensuse.org/opensuse-updates/2015-12/msg00053.html
http://rhn.redhat.com/errata/RHSA-2015-2645.html
http://www.ubuntu.com/usn/USN-2803-1
https://kb.juniper.net/JSA10783
https://access.redhat.com/errata/RHSA-2015:2636
https://access.redhat.com/errata/RHSA-2015:2552
https://access.redhat.com/security/cve/CVE-2015-5307
https://access.redhat.com/errata/RHSA-2015:2645
https://access.redhat.com/errata/RHSA-2015:2587
https://access.redhat.com/errata/RHSA-2016:0004