The affiliate-toolkit WordPress plugin before 3.4.3 lacks authorization and authentication for requests to it's affiliate-toolkit-starter/tools/atkp_imagereceiver.php endpoint, allowing unauthenticated visitors to make requests to arbitrary URL's, including RFC1918 private addresses, leading to a Server Side Request Forgery (SSRF) issue.
https://wpscan.com/vulnerability/39ed4934-3d91-4924-8acc-25759fef9e81