I usually expose ports like `127.0.0.1:1234:1234` instead of `1234:1234`. As far as I understand, it still punches holes this way but to access the container, an attacker would need to get a packet routed to the host with a spoofed IP SRC set to `127.0.0.1`. All other solutions that are better seem to be much more involved.
Worse, the linked bug report is from a DECADE ago, and the comments underneath don't seem to show any sense of urgency or concern about how bad this is.
Have I missed something? This seems appalling.
As for it not being explicitly permitted, no ports are exposed by default. You must provide the docker run command with -p, for each port you want exposed. From their perspective, they're just doing exactly what you told them to do.
Personally, I think it should default to giving you an error unless you specified what IPs to listen to, but this is far from a big of an issue as people make it out to be.
The biggest issue is that it is a ginormous foot gun for people who don't know Docker.
Maybe it's the difference between "-P" and "-p", or specifying both "8080:8080" instead of "8080", but there is a difference, especially since one wouldn't be reachable outside of your machine and the other one would be on worse case trying to bind 0.0.0.0.