Rendertron versions prior to 3.0.0 are are susceptible to a Server-Side Request Forgery (SSRF) attack. An attacker can use a specially crafted webpage to force a rendertron headless chrome process to render internal sites it has access to, and display it as a screenshot. Suggested mitigations are to upgrade your rendertron to version 3.0.0, or, if you cannot update, to secure the infrastructure to limit the headless chrome's access to your internal domain.
The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.