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.
https://bugzilla.redhat.com/show_bug.cgi?id=560654
http://secunia.com/advisories/38492
http://secunia.com/advisories/38499
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10953
https://rhn.redhat.com/errata/RHSA-2010-0088.html