Xen through 4.8.x does not validate a vCPU array index upon the sending of an SGI, which allows guest OS users to cause a denial of service (hypervisor crash), aka XSA-225.

The grant-table feature in Xen through 4.8.x mishandles MMIO region grant references, which allows guest OS users to cause a denial of service (loss of grant trackability), aka XSA-224 bug 3.

The grant-table feature in Xen through 4.8.x does not ensure sufficient type counts for a GNTMAP_device_map and GNTMAP_host_map mapping, which allows guest OS users to cause a denial of service (count mismanagement and memory corruption) or obtain privileged host OS access, aka XSA-224 bug 2.

The grant-table feature in Xen through 4.8.x mishandles a GNTMAP_device_map and GNTMAP_host_map mapping, when followed by only a GNTMAP_host_map unmapping, which allows guest OS users to cause a denial of service (count mismanagement and memory corruption) or obtain privileged host OS access, aka XSA-224 bug 1.

Xen through 4.8.x mishandles virtual interrupt injection, which allows guest OS users to cause a denial of service (hypervisor crash), aka XSA-223.

Xen through 4.8.x does not validate memory allocations during certain P2M operations, which allows guest OS users to obtain privileged host OS access, aka XSA-222.

Xen through 4.8.x does not validate the port numbers of polled event channel ports, which allows guest OS users to cause a denial of service (NULL pointer dereference and host OS crash) or possibly obtain sensitive information, aka XSA-221.

The vCPU context-switch implementation in Xen through 4.8.x improperly interacts with the Memory Protection Extensions (MPX) and Protection Key (PKU) features, which makes it easier for guest OS users to defeat ASLR and other protection mechanisms, aka XSA-220.

The shadow-paging feature in Xen through 4.8.x mismanages page references and consequently introduces a race condition, which allows guest OS users to obtain Xen privileges, aka XSA-219.

The grant-table feature in Xen through 4.8.x has a race condition leading to a double free, which allows guest OS users to cause a denial of service (memory consumption), or possibly obtain sensitive information or gain privileges, aka XSA-218 bug 2.

The grant-table feature in Xen through 4.8.x provides false mapping information in certain cases of concurrent unmap calls, which allows backend attackers to obtain sensitive information or gain privileges, aka XSA-218 bug 1.

Xen through 4.8.x mishandles page transfer, which allows guest OS users to obtain privileged host OS access, aka XSA-217.

Xen through 4.6.x on 64-bit platforms mishandles a failsafe callback, which might allow PV guest OS users to execute arbitrary code on the host OS, aka XSA-215.

Xen 4.5.x through 4.7.x on AMD systems without the NRip feature, when emulating instructions that generate software interrupts, allows local HVM guest OS users to cause a denial of service (guest crash) by leveraging an incorrect choice for software interrupt delivery.

Xen 4.5.x through 4.7.x on AMD systems without the NRip feature, when emulating instructions that generate software interrupts, allows local HVM guest OS users to cause a denial of service (guest crash) by leveraging IDT entry miscalculation.

VMFUNC emulation in Xen 4.6.x through 4.8.x on x86 systems using AMD virtualization extensions (aka SVM) allows local HVM guest OS users to cause a denial of service (hypervisor crash) by leveraging a missing NULL pointer check.

Xen through 4.8.x allows local x86 PV guest OS kernel administrators to cause a denial of service (host hang or crash) by modifying the instruction stream asynchronously while performing certain kernel operations.

Xen through 4.8.x allows local 64-bit x86 HVM guest OS users to gain privileges by leveraging mishandling of SYSCALL singlestep during emulation.

The x86 emulator in Xen does not properly treat x86 NULL segments as unusable when accessing memory, which might allow local HVM guest users to gain privileges via vectors involving "unexpected" base/limit values.

The x86 segment base write emulation functionality in Xen 4.4.x through 4.7.x allows local x86 PV guest OS administrators to cause a denial of service (host crash) by leveraging lack of canonical address checks.