BuddyPress 1.6.4 (now available for download) is a maintenance and security release, and a safe and easy update for all previous BuddyPress versions.
Version 1.6.4 includes some security hardening inside the bp-default theme’s ajax functionality. These issues were responsibly disclosed by Maty Siman.
Download 1.6.4 now or visit Dashboard ? Updates in your site admin to update now.