Doppler Forms <= 2.5.1 - Subscriber+ Limited Plugin Installation

The Doppler Forms WordPress plugin through 2.5.1 registers an AJAX action install_extension without verifying user capabilities or using a nonce. As a result, any authenticated user — including those with the Subscriber role — can install and activate additional Doppler Forms WordPress plugin through 2.5.1 (limited to those whitelisted by the main Doppler Forms WordPress plugin through 2.5.1).