WooPayments <= 10.5.1 - Missing Authorization to Unauthenticated Plugin Settings Update via save_upe_appearance_ajax

The WooPayments: Integrated WooCommerce Payments plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the 'save_upe_appearance_ajax' function in all versions up to, and including, 10.5.1. This makes it possible for unauthenticated attackers to update plugin settings.