Certain legacy functionality in fusermount in fuse 2.8.5 and earlier, when util-linux does not support the --no-canonicalize option, allows local users to bypass intended access restrictions and unmount arbitrary directories via a symlink attack.
http://lists.opensuse.org/opensuse-security-announce/2011-04/msg00000.html
http://www.openwall.com/lists/oss-security/2011/02/02/2