The jail rc.d script in FreeBSD 5.3 up to 6.2 does not verify pathnames when writing to /var/log/console.log during a jail start-up, or when file systems are mounted or unmounted, which allows local root users to overwrite arbitrary files, or mount/unmount files, outside of the jail via a symlink attack.
http://www.securityfocus.com/bid/22011
http://securitytracker.com/id?1017505