An issue was discovered in Xen 4.5.x through 4.9.x allowing attackers (who control a stub domain kernel or tool stack) to cause a denial of service (host OS crash) because of a missing comparison (of range start to range end) within the DMOP map/unmap implementation.
An issue was discovered in Xen through 4.9.x allowing x86 guest OS users to cause a denial of service (hypervisor crash) or possibly gain privileges because MSI mapping was mishandled.
An issue was discovered in Xen through 4.9.x allowing x86 HVM guest OS users to obtain sensitive information from the host OS (or an arbitrary guest OS) because intercepted I/O operations can cause a write of data from uninitialized hypervisor stack memory.
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.
The KVM subsystem in the Linux kernel through 4.2.6, and Xen 4.3.x through 4.6.x, allows guest OS users to cause a denial of service (host OS panic or hang) by triggering many #DB (aka Debug) exceptions, related to svm.c.