Chisel is a TCP/UDP tunnel, transported over HTTP and secured via SSH. In versions prior to 1.11.5, authenticated clients can bypass --authfile ACL restrictions and tunnel traffic to arbitrary destinations reachable from the server. The ACL is enforced only during the initial handshake against declared remotes, but never on subsequent SSH channels that carry actual traffic. A malicious client can authenticate with a permitted remote, then open channels to any host:port it wants. This issue has been fixed in version 1.11.5.

Chisel has an ACL Bypass via Post-Handshake SSH Channel ExtraData Injection