The internal_dump function in Mathopd before 1.5p5, and 1.6x before 1.6b6 BETA, when Mathopd is running with the -n option, allows local users to overwrite arbitrary files via a symlink attack on dump files that are triggered by a SIGWINCH signal.
http://www.mail-archive.com/mathopd%40mathopd.org/msg00272.html