Re:Ask HN: Why does the US Visa application website do a por...
by 77pt77 on Wednesday August 20, 2025 @11:44AM
(#44962970)
This is by far the most likely reason.
I personally use pages that authenticate via a smartcard using this exact scheme.
There is a Java "plugin" that is nothing but a mini webserver that listens on a specific port and performs authentication.
This is a common pattern for connecting to smart cards / hardware security devices. Probably a service or hardware that’s run on official CBP machines that should be disabled for prod, but forgot.