Xen, when running on a 64-bit hypervisor, allows local x86 guest OS users to modify arbitrary memory and consequently obtain sensitive information, cause a denial of service (host crash), or execute arbitrary code on the host by leveraging broken emulation of bit test instructions.
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.
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.
Xen 4.7.x and earlier does not properly honor CR0.TS and CR0.EM, which allows local x86 HVM guest OS users to read or modify FPU, MMX, or XMM register state information belonging to arbitrary tasks on the guest by modifying an instruction while the hypervisor is preparing to emulate it.
Buffer overflow in Xen 4.7.x and earlier allows local x86 HVM guest OS administrators on guests running with shadow paging to cause a denial of service via a pagetable update.
Xen 4.5.3, 4.6.3, and 4.7.x allow local HVM guest OS administrators to overwrite hypervisor memory and consequently gain host OS privileges by leveraging mishandling of instruction pointer truncation during emulation.
Xen 4.5.x through 4.7.x do not implement Supervisor Mode Access Prevention (SMAP) whitelisting in 32-bit exception and event delivery, which allows local 32-bit PV guest OS kernels to cause a denial of service (hypervisor and VM crash) by triggering a safety check.
The PV pagetable code in arch/x86/mm.c in Xen 4.7.x and earlier allows local 32-bit PV guest OS administrators to gain host OS privileges by leveraging fast-paths for updating pagetable entries.
The qemu implementation in libvirt before 1.3.0 and Xen allows local guest OS users to cause a denial of service (host disk consumption) by writing to stdout or stderr.
Heap-based buffer overflow in QEMU 0.8.2, as used in Xen and possibly other products, allows local users to execute arbitrary code via crafted data in the "net socket listen" option, aka QEMU "net socket" heap overflow. NOTE: some sources have used CVE-2007-1321 to refer to this issue as part of "NE2000 network driver and the socket code," but this is the correct identifier for the individual net socket listen vulnerability.