Input validation vulnerability in Newsletters 4.6.5.2

The Newsletters plugin for WordPress versions up to and including 4.6.4.2 is vulnerable to a type of security attack called Reflected Cross-Site Scripting. This means that if an attacker is able to trick a user into clicking on a malicious link, they can potentially inject arbitrary web scripts into the page that a user would see. This is possible because the plugin does not properly check and filter inputs or properly escape outputs.