diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 9329919fb07f..f64f7a35b5c9 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -1362,6 +1362,9 @@ static void tipc_sk_conn_proto_rcv(struct tipc_sock *tsk, struct sk_buff *skb,
 			__skb_queue_tail(xmitq, skb);
 		return;
 	} else if (mtyp == CONN_ACK) {
+		if (tsk->snt_unacked < msg_conn_ack(hdr))
+			goto exit;
+
 		was_cong = tsk_conn_cong(tsk);
 		tipc_sk_push_backlog(tsk, msg_nagle_ack(hdr));
 		tsk->snt_unacked -= msg_conn_ack(hdr);