This update for xen fixes the following issues: - A Mishandling of SYSCALL singlestep during emulation which could have lead to privilege escalation. - CMPXCHG8B emulation failed to ignore operand size override which could have lead to information disclosure. - PV guests may have been able to mask interrupts causing a Denial of Service. - A missing NULL pointer check in VMFUNC emulation could lead to a hypervisor crash leading to a Denial of Servce