Fun-reliable side-channels for cross-container communication (h4x0r.org)

Here's a recipe for running the proof of concept using Docker on a Mac:

  cd /tmp
  wget https://github.com/crashappsec/h4x0rchat/blob/9b9d0bd5b2287501335acca35d070985e4f51079/h4x0rchat.c
  docker run --rm -it -v "$PWD:/src" \
    -w /src gcc:13 bash -lc 'gcc -Wall -O2 \
    -o h4x0rchat h4x0rchat.c && ./h4x0rchat'

Animated screenshot demo here: https://simonwillison.net/2025/Nov/12/h4x0rchat/

That is a fun read. Shared systems indeed share outside their designer's intent.