Problem

handleSendRawTransaction deserializes the supplied hex into a wire.MsgTx but never verifies that the entire input was consumed:

var msgTx wire.MsgTx
err = msgTx.Deserialize(bytes.NewReader(serializedTx))

MsgTx.Deserialize reads exactly the bytes that make up a transaction and stops, so any extra bytes appended after a fully-formed transaction are silently discarded — and the transaction is still accepted and relayed.

This diverges from bitcoind, whose sendrawtransaction rejects such input with a deserialization error (TX decode failed) instead of broadcasting a transaction parsed from a malformed payload.

Fix

Read the serialized transaction through a *bytes.Reader and, after a successful Deserialize, check that no unread bytes remain. If any are left over, return ErrRPCDeserialization, matching Core's behavior.

This mirrors the same trailing-bytes hardening applied to decoderawtransaction in #2550 and to the PSBT global unsigned tx in #2541 — completing the set across the RPC tx-decode paths.

Test

TestHandleSendRawTransactionTrailingBytes appends a spurious byte to an otherwise valid transaction and asserts the handler now returns ErrRPCDeserialization. Verified red before the fix (the handler proceeded past deserialization) and green after.

go build ./..., go vet ., gofmt -l and the RPC handler tests all pass.