EA2700 WAN PORT open to the world by default?

Question

I just noticed last night that my EA2700 router was accessible on the WAN port, from the Internet, on ports 80 and 53. I am running router firmware 1.0.14 and the update utility reports that there is no newer version.
Remote management is NOT enabled (it defaults to port 8080 anyway) and I enabled and disabled it for good measure. Rebooted a few times, too.
I then enabled and disabled the regular admin interface on HTTPS and turned off HTTP. That enabled the admin interface on port 443, but still left it enabled on port 80. And now both port 80 and 443 were accessible outside the firewall! And now I couldn't turn off port 443!
I disabled UPnP and rebooted and still the ports were open to the Internet.
Needless to say, I was pretty horrified by this discovery.
I only leave one port forwarded, port 22, to SSH on an internal box. That is the only hole through my firewall I ever expect to see.
As a fix for this problem, I added three new port forwards on port 80, port 53 and port 443, and mapped them all to a random port on an unused IP on my internal network. THIS and ONLY this finally made ports 80, 53, and 443 inaccessible from the Internet at large.
What's going on here? It seems hard to believe that EVERY EA2700 device would have this issue or this would've come out long ago. Any ideas?

Answer 1

https://superevr.com/blog/2013/dont-use-linksys-routers/