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.
http://lists.opensuse.org/opensuse-security-announce/2016-03/msg00094.html
http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00045.html
http://lists.opensuse.org/opensuse-security-announce/2016-07/msg00005.html
http://www.debian.org/security/2016/dsa-3434
http://www.debian.org/security/2016/dsa-3471
http://www.debian.org/security/2016/dsa-3519
http://www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.html
http://www.securityfocus.com/bid/79592
http://www.securitytracker.com/id/1034479
Source: MITRE
Published: 2016-04-14
Updated: 2017-11-04
Type: CWE-284
Base Score: 5.7
Vector: AV:L/AC:L/Au:S/C:P/I:P/A:C
Impact Score: 8.5
Exploitability Score: 3.1
Severity: MEDIUM
Base Score: 8.2
Vector: CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Impact Score: 6
Exploitability Score: 1.5
Severity: HIGH