The x86 emulator in KVM 83 does not use the Current Privilege Level (CPL) and I/O Privilege Level (IOPL) in determining the memory access available to CPL3 code, 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, a related issue to CVE-2010-0306.