The x86 emulator in KVM 83, when a guest is configured for Symmetric Multiprocessing (SMP), does not use the Current Privilege Level (CPL) and I/O Privilege Level (IOPL) to restrict instruction execution, which allows guest OS users to cause a denial of service (guest OS crash) or gain privileges on the guest OS by leveraging access to a (1) IO port or (2) MMIO region, and replacing an instruction in between emulator entry and instruction fetch, a related issue to CVE-2010-0298.