UpdraftPlus <= 1.23.3 - Cross-Site Request Forgery to Cross-Site Scripting via action_authenticate_storage

The UpdraftPlus plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 1.23.3. This is due to missing or incorrect nonce validation on the action_authenticate_storage function. This makes it possible for unauthenticated attackers to inject JavaScript into a parameter in the authentication process via a forged request which will execute in their browser at another part of the process, granted they can trick a site administrator into performing multiple actions including re-authenticating a connection to storage.