WPO365 | MICROSOFT 365 GRAPH MAILER <= 3.2 - Open Redirect via 'redirect_to' Parameter

The WPO365 | MICROSOFT 365 GRAPH MAILER plugin for WordPress is vulnerable to Open Redirect in all versions up to, and including, 3.2. This is due to insufficient validation on the redirect url supplied via the 'redirect_to' parameter. This makes it possible for unauthenticated attackers to redirect users to potentially malicious sites if 1. they can successfully trick them into performing an action and 2. the plugin is activated but not configured.