Use-after-free vulnerability in Xen 4.2.x, 4.3.x, and 4.4.x allows remote domains to cause a denial of service (system crash) via a crafted hypercall during HVM guest teardown.
https://security.gentoo.org/glsa/201504-04
http://xenbits.xen.org/xsa/advisory-116.html
http://www.securitytracker.com/id/1031498
http://www.securityfocus.com/bid/71882
http://lists.opensuse.org/opensuse-security-announce/2015-02/msg00010.html
http://lists.opensuse.org/opensuse-security-announce/2015-02/msg00005.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-January/148241.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-January/148103.html