bbPress 2.5.8 is out now, and it fixes several issues regarding user query parsing and hardening of ajax actions for logged out users for all previous bbPress 2.x installations. If you’re using any version of bbPress 2.x and have not yet updated, please do so right away. If you need help, please reach out in our support forums and someone will be happy to assist you.

These fixes have also been ported over to 2.6, which we continue to run here at bbPress.org and BuddyPress.org.