xend in Xen 3.0.3 does not properly limit the contents of the /local/domain xenstore directory tree, and does not properly restrict a guest VM's write access within this tree, which allows guest OS users to cause a denial of service and possibly have unspecified other impact by writing to (1) console/tty, (2) console/limit, or (3) image/device-model-pid.  NOTE: this issue was originally reported as an issue in libvirt 0.3.3 and xenstore, but CVE is considering the core issue to be related to Xen.