Divi Membership <= 2.2.0 - Unauthenticated Privilege Escalation via 'form_id' Parameter

The Divi Membership plugin for WordPress is vulnerable to Privilege Escalation in versions up to, and including, 2.2.0. This is due to the `dmem_form_submit_handler()` function determining the new user's role by iterating all WordPress roles and calling `password_verify()` against an attacker-controlled bcrypt hash supplied in the `form_id` POST parameter, with no validation or whitelist of allowed roles. This makes it possible for unauthenticated attackers to register a new account with the administrator role by submitting a locally computed bcrypt hash of `administrator` as `form_id`, and when `auto_login=on` is submitted, be immediately authenticated as that administrator in the same request, resulting in full site takeover. Exploitation requires a WordPress nonce, but that nonce is publicly emitted on any page rendering the Divi Membership registration form and is therefore obtainable by any unauthenticated visitor.

Quoted source text, attributed separately from HOL analysis.