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.

References

• https://nvd.nist.gov/vuln/detail/CVE-2020-8902
• https://github.com/GoogleChrome/rendertron/releases/tag/3.0.0
• https://www.npmjs.com/package/rendertron