Description
Clickjacking (User Interface redress attack, UI redress attack, UI redressing) is a malicious technique of tricking a Web user into clicking on something different from what the user perceives they are clicking on, thus potentially revealing confidential information or taking control of their computer while clicking on seemingly innocuous web pages.
The server didn't return a frame-ancestors directive in the Content-Security-Policy header which means that this website could be at risk of a clickjacking attack. The frame-ancestors directives can be used to indicate whether or not a browser should be allowed to render a page inside a frame. Sites can use this to avoid clickjacking attacks, by ensuring that their content is not embedded into other sites.
Remediation
Configure your web server to include a CSP header with frame-ancestors directive and an X-Frame-Options header. Consult Web references for more information about the possible values for this header.