There’s a few of these, off the top of my head: https://capnproto.org/ and Apache Arrow Flight https://github.com/apache/arrow/pull/2102
I guess I don’t understand why there’s so many in this space - byte-for-byte interchange requires a schema and a predictable layout; beyond that I don’t know why there would be a need for multiple such systems. Of course, I don’t use these libraries - I use Avro for when I need this kind of thing (mostly because of tooling/interop in the big data space).
I know Cap n Proto is security focused. Most aren’t despite how many attackers will aim at them.