Xen 4.3.x, 4.4.x, and 4.5.x, when using toolstack disaggregation, allows remote domains with partial management control to cause a denial of service (host lock) via unspecified domctl operations.
https://security.gentoo.org/glsa/201504-04
http://xenbits.xen.org/xsa/advisory-127.html
http://www.securitytracker.com/id/1031997
http://www.securityfocus.com/bid/73443
http://lists.opensuse.org/opensuse-security-announce/2015-05/msg00018.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-April/155198.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-April/154579.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-April/154574.html