The FULL - Customer plugin for WordPress is vulnerable to Arbitrary File Upload via the /install-plugin REST route in versions up to, and including, 2.2.3 due to improper authorization. This allows authenticated attackers with subscriber-level permissions and above to execute code by installing plugins from arbitrary remote locations including non-repository sources onto the site, granted they are packaged as a valid WordPress plugin.
https://plugins.trac.wordpress.org/browser/full-customer/tags/2.2.1/app/api/PluginInstallation.php
https://plugins.trac.wordpress.org/browser/full-customer/tags/1.1.0/app/api/Plugin.php