FreeBSD Security Advisory FreeBSD-SA-00:76 - The csh and tcsh code creates temporary files when the double less than operator is used, however these are created insecurely and use a predictable filename based on the process ID of the shell. An attacker can exploit this vulnerability to overwrite an arbitrary file writable by the user running the shell. The contents of the file are overwritten with the text being entered using the double less than operator, so it will usually not be under the control of the attacker, limiting the scope of this vulnerability to denial of service.