fuse 2.8.5 and earlier does not properly handle when /etc/mtab cannot be updated, which allows local users to unmount arbitrary directories via a symlink attack.
http://www.openwall.com/lists/oss-security/2011/02/08/4
http://www.openwall.com/lists/oss-security/2011/02/03/5
http://www.openwall.com/lists/oss-security/2011/02/02/2
http://lists.opensuse.org/opensuse-security-announce/2011-04/msg00000.html