An issue was discovered in Xen through 4.11.x on AMD x86 platforms, possibly allowing guest OS users to gain host OS privileges because TLB flushes do not always occur after IOMMU mapping changes.
lists.opensuse.org/opensuse-security-announce/2019-04/msg00072.html
www.securityfocus.com/bid/106182
lists.debian.org/debian-lts-announce/2019/10/msg00008.html
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UXC6BME7SXJI2ZIATNXCAH7RGPI4UKTT/
support.citrix.com/article/CTX239432
www.debian.org/security/2019/dsa-4369
xenbits.xen.org/xsa/advisory-275.html