Bokken before 1.6 and 1.5-x before 1.5-3 for Debian allows local users to overwrite arbitrary files via a symlink attack on /tmp/graph.dot.
http://secunia.com/advisories/47252
http://ingumadev.blogspot.com/2012/01/bokken-16-is-more-stable-and-easier-to.html
http://inguma.eu/projects/bokken/repository/revisions/56894084b0ec