Rendertron 1.0.0 includes an _ah/stop route to shutdown the Chrome instance responsible for serving render requests to all users. Visiting this route with a GET request allows any unauthorized remote attacker to disable the core service of the application.
https://github.com/GoogleChrome/rendertron/pull/88
https://github.com/GoogleChrome/rendertron/commit/8d70628c96ae72eff6eebb451d26fc9ed6b58b0e