FreeBSD 2.1.6 Security Update
A serious security problem affecting FreeBSD 2.1.6 and earlier systems was found. The problem has been corrected within the -stable, -current, and RELENG_2_2 source trees. As an additional precaution, FreeBSD 2.1.6 is no longer available from the FTP distribution sites. An update release (provisionally "FreeBSD 2.1.7") is expected shortly.
You can read more about the problem and solution from the FreeBSD-SA-97:01.setlocale security announcement.