Disconnect peers sending wtxidrelay message after VERACK

src/net_processing.cpp

@@ -2506,6 +2506,12 @@ void ProcessMessage(
     // Feature negotiation of wtxidrelay should happen between VERSION and
     // VERACK, to avoid relay problems from switching after a connection is up
     if (msg_type == NetMsgType::WTXIDRELAY) {
+        if (pfrom.fSuccessfullyConnected) {
+            // Disconnect peers that send wtxidrelay message after VERACK; this
+            // must be negotiated between VERSION and VERACK.
+            pfrom.fDisconnect = true;
+            return;
+        }
         if (pfrom.nVersion >= WTXID_RELAY_VERSION) {
             LOCK(cs_main);
             if (!State(pfrom.GetId())->m_wtxid_relay) {