Sonic 3 A.I.R. before commit 2492d18 contains a missing source address validation vulnerability in ConnectionManager where established connections are resolved by a two-byte local connection handle alone without verifying that the datagram source address matches the registered remote address for the connection. An on-path attacker who can observe cleartext UDP traffic can inject arbitrary packets into any established session by forging the two-byte connection identifier, enabling session termination via TerminateConnectionPacket, arbitrary channel message forgery, and forged request responses without requiring IP address spoofing.