The PDF Invoices and Packing Slips For WooCommerce plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 1.3.7 via deserialization of untrusted input via the order_id parameter.
Deserialization of Untrusted Data vulnerability in Acowebs PDF Invoices and Packing Slips For WooCommerce.This issue affects PDF Invoices and Packing Slips For WooCommerce: from n/a through 1.3.7.