The KIWIZ Invoices Certification & PDF System WordPress plugin through 2.1.3 does not validate the path of files to be downloaded, which could allow unauthenticated attacker to read/downlaod arbitrary files, as well as perform PHAR unserialization (assuming they can upload a file on the server)
https://wpscan.com/vulnerability/4d3b90d8-8a6d-4b72-8bc7-21f861259a1b