Invoice123 <= 1.7.0 - Missing Authorization to Authenticated (Subscriber+) Setting Modification via s123_submit_api_key & s123_submit_invoice_settings AJAX actions

The Invoice123 plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 1.7.0. This is due to the plugin not properly verifying that a user is authorized to perform an action. This makes it possible for authenticated attackers, with subscriber-level access and above, to overwrite the plugin's API key stored in wp_options, modify invoice plugin settings, and alter WooCommerce tax rate data in the wp_woocommerce_tax_rates table.