A .plan update by id Software programmer Robert Duffy gives word of a new Quake III Arena 1.16i Beta update now on the id Software FTP server. Here is a local copy of the Windows patch (401 KB), the Linux patch (619 KB), and the Mac patch (387 KB), each with a list of mirrors. Here's the entirety of the brief .plan update, which indicates this addresses security:

Q3A 1.16i Beta is now on our ftp site. This is a small executable only patch that enhances security. It is available in three flavors, Win32 ( a .zip file ), Linux ( a .gz ) and Macintosh ( a self extracting archive ).

This is the note on exactly what security this involves from the accompanying read me file(s):

This update adds an additional layer of CD Key security.

When you type your CD Key in, the letters and numbers will appear as they normally would. If you leave the screen and return at a later time, blank spaces replace all the characters.