Index: obuspa-10.0.6.0/src/core/device.h
===================================================================
--- obuspa-10.0.6.0.orig/src/core/device.h
+++ obuspa-10.0.6.0/src/core/device.h
@@ -355,6 +355,10 @@ void DEVICE_CONTROLLER_SetInheritedRole(
 int DEVICE_CONTROLLER_CountEnabledWebsockClientConnections(void);
 #endif
 
+#ifdef OBUSPA_CONTROLLER_MTP_VERIFY
+bool DEVICE_CONTROLLER_IsMTPAllowed(char *endpoint_id, mtp_conn_t *mpc);
+#endif
+
 #ifndef REMOVE_USP_BROKER
 int DEVICE_SUBSCRIPTION_RouteNotification(Usp__Msg *usp, int instance, char *subscribed_path);
 bool DEVICE_SUBSCRIPTION_MarkVendorLayerSubs(int broker_instance, subs_notify_t notify_type, char *path, int group_id);
Index: obuspa-10.0.6.0/src/core/device_controller.c
===================================================================
--- obuspa-10.0.6.0.orig/src/core/device_controller.c
+++ obuspa-10.0.6.0/src/core/device_controller.c
@@ -969,6 +969,78 @@ int DEVICE_CONTROLLER_QueueBinaryMessage
     return USP_ERR_OK;
 }
 
+#ifdef OBUSPA_CONTROLLER_MTP_VERIFY
+/*********************************************************************//**
+**
+** DEVICE_CONTROLLER_IsMTPAllowed
+**
+** Determines whether an MTP is allowed to be used by the specified controller
+** This function is used by ValidateUspRecord() to determine whether to process a received USP message
+**
+** \param   endpoint_id - Endpoint ID of controller that sent a USP message
+** \param   mpc - pointer to structure specifying on which MTP the message was received
+**
+** \return  true if the MTP is allowed, false otherwise
+**
+**************************************************************************/
+bool DEVICE_CONTROLLER_IsMTPAllowed(char *endpoint_id, mtp_conn_t *mpc)
+{
+    controller_t *cont = FindEnabledControllerByEndpointId(endpoint_id);
+    controller_mtp_t *mtp;
+
+    // Disallow if no controller instance is found
+    if (cont == NULL)
+    {
+        return false;
+    }
+
+    mtp = FindFirstEnabledMtp(cont, mpc->protocol);
+
+#ifdef ENABLE_WEBSOCKETS
+    // Allow websocket server if no other MTP is configured
+    if ((mpc->protocol == kMtpProtocol_WebSockets) && (mpc->ws.serv_conn_id != INVALID))
+    {
+        return mtp == NULL;
+    }
+#endif
+
+    // Disallow if there is no MTP configured with matching protocol
+    if ((mtp == NULL) || (mtp->protocol != mpc->protocol))
+    {
+        return false;
+    }
+
+    // Check that the configured MTP matches the MTP on which the message was received
+    switch(mtp->protocol)
+    {
+#ifndef DISABLE_STOMP
+        case kMtpProtocol_STOMP:
+            return mtp->stomp_connection_instance == mpc->stomp.instance;
+#endif
+
+#ifdef ENABLE_COAP
+        case kMtpProtocol_CoAP:
+            return true;  // More detailed checks are not implemented for CoAP
+#endif
+
+#ifdef ENABLE_MQTT
+        case kMtpProtocol_MQTT:
+            return mtp->mqtt_connection_instance == mpc->mqtt.instance;
+#endif
+
+#ifdef ENABLE_WEBSOCKETS
+        case kMtpProtocol_WebSockets:
+            return (mpc->ws.client_cont_instance == cont->instance) && (mpc->ws.client_mtp_instance == mtp->instance);
+#endif
+        default:
+            TERMINATE_BAD_CASE(mtp->protocol);
+            break;
+    }
+
+    return false;
+}
+#endif
+
 /*********************************************************************//**
 **
 ** DEVICE_CONTROLLER_IsMTPConfigured
Index: obuspa-10.0.6.0/src/core/msg_handler.c
===================================================================
--- obuspa-10.0.6.0.orig/src/core/msg_handler.c
+++ obuspa-10.0.6.0/src/core/msg_handler.c
@@ -1344,6 +1344,15 @@ int ValidateUspRecord(UspRecord__Record
     usp_service_instance = USP_BROKER_GetUspServiceInstance(rec->from_id, 0);
 #endif
 
+#ifdef OBUSPA_CONTROLLER_MTP_VERIFY
+    // Exit if the controller is not allowed to use the MTP on which the message was received
+    if (DEVICE_CONTROLLER_IsMTPAllowed(rec->from_id, mtpc) == false)
+    {
+        USP_ERR_SetMessage("%s: Ignoring message from endpoint_id=%s (unauthorized MTP)", __FUNCTION__, rec->from_id);
+        return USP_ERR_PERMISSION_DENIED;
+    }
+#endif
+
     // Exit if the endpoint sending the message is unknown
     cur_msg_controller_instance = DEVICE_CONTROLLER_FindInstanceByEndpointId(rec->from_id);
     if ((cur_msg_controller_instance == INVALID) && (usp_service_instance == INVALID))
