The bdrv_open function in Qemu 1.0 does not properly handle the failure of the mkstemp function, when in snapshot node, which allows local users to overwrite or read arbitrary files via a symlink attack on an unspecified temporary file.
http://lists.opensuse.org/opensuse-security-announce/2012-09/msg00024.html
http://secunia.com/advisories/50132
http://secunia.com/advisories/50689