An issue was discovered in Xen through 4.9.x allowing x86 PV guest OS users to execute arbitrary code on the host OS because of a race condition that can cause a stale TLB entry.
http://www.securityfocus.com/bid/101490
http://www.securitytracker.com/id/1039568
https://lists.debian.org/debian-lts-announce/2017/11/msg00027.html
https://lists.debian.org/debian-lts-announce/2018/10/msg00009.html
https://security.gentoo.org/glsa/201801-14
https://support.citrix.com/article/CTX228867
Source: MITRE
Published: 2017-10-18
Updated: 2018-10-19
Type: CWE-362
Base Score: 6.9
Vector: AV:L/AC:M/Au:N/C:C/I:C/A:C
Impact Score: 10
Exploitability Score: 3.4
Severity: MEDIUM
Base Score: 7.8
Vector: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Impact Score: 6
Exploitability Score: 1.1
Severity: HIGH