The wpForo Forum plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 3.1.5. This is due to the plugin not properly verifying that a user is authorized to perform an action. This makes it possible for authenticated attackers, with subscriber-level access and above, to take over another guest author's forum post and modify its title, body, author name, and stored owner email address. This requires that guest posting and editing are enabled on the forum, and that the attacker knows the target guest author's email address.