WCPOS <= 1.9.14 - Authenticated (Shop Manager+) Code Injection via 'thermal' Template Engine

The WCPOS – Point of Sale (POS) plugin for WooCommerce plugin for WordPress is vulnerable to Code Injection via the 'thermal' Template Engine in all versions up to, and including, 1.9.14 due to the Receipt_Renderer_Factory dispatching templates with the 'thermal' engine to the Legacy_Php_Renderer instead of a safe thermal-specific renderer. This makes it possible for authenticated attackers, with Shop Manager-level access and above, to inject arbitrary PHP code into a template post that is subsequently written to a temporary file and executed via PHP's include(), resulting in remote code execution on the server. This requires the attacker to have Shop Manager-level access or above, as the template save path enforces a wcpos_template_settings nonce and the manage_woocommerce_pos capability check.