The plugin does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup).
Proof of Concept
Put the following payload in the Name field of WooCommerce > Settings > DPD > Warehouses: "><script>alert(/XSS/);</script>
Fill the other fields with dummy data and save. The XSS will be triggered in all backend pages.