When you hear about someone jail breaking an iphone trough the browser, this is how. The fact that the browser works as a window to all tcp-sockets running on a device, it's the perfect way to exploit buffert overflows on a device that lacks a terminal.

Also remember this with all your IoT appliances running on your local network. Even if it has a local IP-address, as long as you have a computer with a browser on the same network, you might as well consider your devices being publicly accessible from the rest of the internet.