The LXC driver (lxc/lxc_driver.c) in libvirt 1.0.1 through 1.2.1 allows local users to (1) delete arbitrary host devices via the virDomainDeviceDettach API and a symlink attack on /dev in the container; (2) create arbitrary nodes (mknod) via the virDomainDeviceAttach API and a symlink attack on /dev in the container; and cause a denial of service (shutdown or reboot host OS) via the (3) virDomainShutdown or (4) virDomainReboot API and a symlink attack on /dev/initctl in the container, related to "paths under /proc/$PID/root" and the virInitctlSetRunLevel function.
https://bugzilla.redhat.com/show_bug.cgi?id=1045643
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=732394
http://www.securityfocus.com/bid/65743
http://security.libvirt.org/2013/0018.html
http://security.gentoo.org/glsa/glsa-201412-04.xml
http://secunia.com/advisories/60895
http://secunia.com/advisories/56215
http://secunia.com/advisories/56187
http://lists.opensuse.org/opensuse-updates/2014-05/msg00004.html
http://lists.fedoraproject.org/pipermail/package-announce/2014-February/129199.html
http://libvirt.org/git/?p=libvirt.git%3Ba=commit%3Bh=5fc590ad9f4