Multiple HVM control operations in Xen 3.4 through 4.2 allow local HVM guest OS administrators to cause a denial of service (physical CPU consumption) via a large input.
https://exchange.xforce.ibmcloud.com/vulnerabilities/80484
http://www.securityfocus.com/bid/56796
http://www.openwall.com/lists/oss-security/2012/12/03/10
http://support.citrix.com/article/CTX135777
http://security.gentoo.org/glsa/glsa-201309-24.xml
http://secunia.com/advisories/55082
http://secunia.com/advisories/51487
http://secunia.com/advisories/51486
http://secunia.com/advisories/51397
http://lists.opensuse.org/opensuse-security-announce/2014-03/msg00021.html
http://lists.opensuse.org/opensuse-security-announce/2012-12/msg00001.html