An issue was discovered in Xen through 4.14.x allowing x86 HVM and PVH guest OS users to cause a denial of service (data corruption), cause a data leak, or possibly gain privileges because coalescing of per-page IOMMU TLB flushes is mishandled.
https://xenbits.xen.org/xsa/advisory-346.html
https://www.debian.org/security/2020/dsa-4804
https://security.gentoo.org/glsa/202011-06
http://xenbits.xen.org/xsa/advisory-346.html
http://www.openwall.com/lists/oss-security/2021/01/19/8
http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00025.html
http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00075.html