The fbld instruction emulation in Xen 3.3.x through 4.3.x does not use the correct variable for the source effective address, which allows local HVM guests to obtain hypervisor stack information by reading the values used by the instruction.
Xen 4.0 through 4.3.x, when using AVX or LWP capable CPUs, does not properly clear previous data from registers when using an XSAVE or XRSTOR to extend the state components of a saved or restored vCPU after touching other restored extended registers, which allows local guest OSes to obtain sensitive information by reading the registers.
The vmx_set_uc_mode function in Xen 3.3 through 4.3, when disabling caches, allows local HVM guests with access to memory mapped I/O regions to cause a denial of service (CPU consumption and possibly hypervisor or guest kernel panic) via a crafted GFN range.
The Intel VT-d Interrupt Remapping engine in Xen 3.3.x through 4.3.x allows local guests to cause a denial of service (kernel panic) via a malformed Message Signaled Interrupt (MSI) from a PCI device that is bus mastering capable that triggers a System Error Reporting (SERR) Non-Maskable Interrupt (NMI).
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.