The bLoyal: Loyalty & Promotions by bLoyal plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 3.1.611.78. This is due to the AJAX actions save_bloyal_configuration_data and save_bloyal_accesskeyverification_data being registered without any capability or nonce checks, and the bloyal_customer_auto_login function unconditionally trusting the Customer.ExternalId value returned by whichever API URL is stored in the plugins options. This makes it possible for authenticated attackers, with Subscriber-level access and above, to overwrite the plugins bLoyal Loyalty Engine API URL (bloyal_custom_loyaltyengine_api_url) and the is_bloyal_custom_api_url flag via the unprotected AJAX actions, then trigger the unauthenticated /cart REST route to cause bloyal_customer_auto_login to fetch customer data from an attacker-controlled endpoint and call wp_set_auth_cookie() with an attacker-supplied Customer.ExternalId, thereby authenticating as any WordPress user including the site Administrator.
The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.