wpForo Forum WordPress plugin: subscribers can escalate to forum admin

The wpForo Forum plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 3.2.2 via the data[secondary_groupids] parameter of the wpforo_action_profile_update POST handler. This is due to a type-confusion flaw in the secondary_groupids authorization guard within the Members::update() function in classes/Members.php, where casting a scalar CSV string (e.g. "0,1") with (array) before array_map('intval', …) and array_filter() produces an empty array — causing the guard's outer conditional, and the else-branch that would otherwise strip the field from the update, to be bypassed entirely — while encode()/decode() downstream correctly explodes the original CSV and persists the attacker-supplied group IDs to wp_wpforo_profiles.secondary_groupids. This makes it possible for authenticated attackers, with Subscriber-level access and above, to escalate their forum privileges to wpForo Administrator by injecting the privileged Admin group ID, granting access to the Forum Accesses editor and the ability to rewrite forum-wide capability policies for all members and edit arbitrary content owned by other users. Exploitation requires the attacker to have at least 3 approved wpForo posts to satisfy the plugin's default antispam gate, along with a valid wpforo nonce obtained from their own account profile form.