PilotPress WordPress plugin: subscriber takes over an Administrator account

The PilotPress plugin for WordPress is vulnerable to Privilege Escalation via Account Takeover in all versions up to, and including, 2.0.43. The vulnerability exists because the update_cc_details() AJAX handler forwards an attacker-supplied username parameter to ONTRAPORT via api_call('update_cc_details', ...) before performing the local username_exists() collision check, and aborts without rolling back the remote rename when a collision is detected — leaving the remote ONTRAPORT contact renamed to an existing WordPress Administrator's login. On a subsequent login attempt, user_login() (hooked to wp_authenticate) authenticates against ONTRAPORT using the renamed login and the attacker's own password, resolves the local WordPress user row via get_user_by('login', $username) — which now selects the real Administrator's row — and calls wp_set_password() against that Administrator's user ID; because the user_level != 10 guard only suppresses PilotPress's own cookie issuance rather than returning a WP_Error to core, WordPress proceeds to validate the newly-synchronized password and issues a full Administrator authentication cookie to the attacker. This makes it possible for authenticated attackers with Subscriber-level access and above — specifically any PilotPress member holding a valid ONTRAPORT contact and the Customer Center nonce — to fully take over an Administrator account.