When using wrangler dev (and wrangler dev --local) without specifying an IP address, Wrangler will listen on every IP address that is accessible from the current machine. While this is very useful, especially if you want to test on a mobile device, it is not an ideal default. A user could unknowingly expose the Worker outside of their machine to any other machine on the network.

In remote dev mode, we do, at least, print the IP addresses on which Wrangler is listening. But I don't believe that we display this stuff when using local dev mode.