GHSA-hmj8-5xmh-5573: libp2p: yamux connection DoS via oversized data frame

The yamux stream multiplexer in py-libp2p does not validate incoming DATA frame lengths against the receive window before reading the frame body. Any peer that completes a standard libp2p handshake can send a single 12-byte frame claiming a 4 GB body, causing the victim’s yamux read loop to block indefinitely. This affects the default new_host() configuration and requires no special setup on either side.