[GHSA] GHSA-6983-jfq8-485w (high) — Phoenix: Unbounded channel joins per transport enables DoS over few connections

GHSA-6983-jfq8-485w Severity: high CVE: CVE-2026-56811

Phoenix: Unbounded channel joins per transport enables DoS over few connections

### Summary

Phoenix transports do not limit the number of channels in a given connection, making it easy to spawn hundreds of thousands of processes over a single connection, and, eventually reaching the max processes VM limit. The solution is to limit the numbe