The KB Support – WordPress Help Desk and Knowledge Base plugin for WordPress is vulnerable to unauthorized access and modification of data due to a missing capability check on the 'kbs_ajax_load_front_end_replies' and 'kbs_ajax_mark_reply_as_read' functions in all versions up to, and including, 1.6.6. This makes it possible for unauthenticated attackers to read replies of any ticket, and mark any reply as read.