Automation Web Platform <= 4.8.6 - Unauthenticated Privilege Escalation via 'wawp_custom_fields' Parameter

The Automation Web Platform – Notifications and OTP for WooCommerce, Advanced Country Code plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 4.8.6. This is due to missing permission enforcement on the publicly accessible REST route `POST /wp-json/wawp/v1/signup/` and the absence of a key allowlist in the `finish_registration_logic` function, which copies the attacker-controlled `wawp_custom_fields` parameter directly into `update_user_meta()` — allowing sensitive meta keys such as `wp_capabilities` and `wp_user_level` to be set by the caller. This makes it possible for unauthenticated attackers to register a new account with the administrator role and gain full administrative access to the site. When OTP verification is enabled at signup, the OTP session token (`otp_transient`) is returned in plaintext in the HTTP response body, and the `handle_magic_link_request()` handler marks that token as verified on any unauthenticated GET request containing it without ever checking the OTP code value — making the OTP step trivially bypassable with no inbox or SMS access required.