The HVMOP_inject_msi function in Xen 4.2.x, 4.3.x, and 4.4.x allows local guest HVM administrators to cause a denial of service (host crash) via a large number of crafted requests, which trigger an error messages to be logged.
http://lists.fedoraproject.org/pipermail/package-announce/2014-June/134710.html
http://lists.fedoraproject.org/pipermail/package-announce/2014-June/134739.html
http://lists.opensuse.org/opensuse-security-announce/2014-10/msg00002.html
http://lists.opensuse.org/opensuse-security-announce/2014-10/msg00003.html
https://security.gentoo.org/glsa/201504-04
http://www.openwall.com/lists/oss-security/2014/06/04/13