The Quick Contact Form plugin for WordPress is vulnerable to a type of cyber attack called Cross-Site Scripting. This means that in versions of the plugin before 6.1, attackers can insert malicious web scripts into the plugin through the ‘qcfname4’ parameter. This malicious code can then execute in the browsers of people who use the plugin, giving the attackers access to private information. It is important to make sure you are running the latest version of the plugin to protect yourself from this kind of attack.