GD Security Headers is a brand new plugin available for free on WordPress.org that will help you set up HTTP security headers and receive reports when CSP and XXS Protection directives have been violated.
Content Security Policy (or CSP) is very complex and powerful security-related HTTP header, that might be complex to implement, but essential in limiting what browser is allowed to load when browsing your website.
Referrer Policy is a new HTTP header drafted in 2015, implemented last year. This header controls referrer header value browser sends when the user is navigating away from your website pages.
Response to each request made to the server from the client side (browser) returns the content and the special block with HTTP response headers containing various information about the content.
GD Security Toolbox Pro 2.0 is a major update to the plugin with several new addons included (total of 14 now), huge changes to some parts of the plugin, many more new features, updates and fixes.
GD Security Toolbox Pro 1.4 is the new update for this WordPress security plugin with the support for Referrer Privacy HTTP header (tweaks and .htaccess), updated libraries and various other improvements.