The Spam protection, Anti-Spam, FireWall by CleanTalk plugin for WordPress is vulnerable to unauthorized Arbitrary Plugin Installation due to an missing empty value check on the api_key value in the perform function in all versions up to, and including, 6.44. This makes it possible for unauthenticated attackers to install and activate arbitrary plugins which can be leveraged to achieve remote code execution if another vulnerable plugin is installed and activated.
The product does not properly anticipate or handle exceptional conditions that rarely occur during normal operation of the product.