--- old/src/java.xml.ws/share/classes/com/sun/xml/internal/ws/protocol/soap/ServerMUTube.java	2017-10-24 14:21:40.232129927 +0100
+++ new/src/java.xml.ws/share/classes/com/sun/xml/internal/ws/protocol/soap/ServerMUTube.java	2017-10-24 14:21:39.940129928 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -30,6 +30,8 @@
 import com.sun.xml.internal.ws.client.HandlerConfiguration;
 import javax.xml.namespace.QName;
 import java.util.Set;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 /**
  * @author Rama Pulavarthi
@@ -40,6 +42,7 @@
     private ServerTubeAssemblerContext tubeContext;
     private final Set<String> roles;
     private final Set<QName> handlerKnownHeaders;
+    private final Lock lock = new ReentrantLock();
 
     public ServerMUTube(ServerTubeAssemblerContext tubeContext, Tube next) {
         super(tubeContext.getEndpoint().getBinding(), next);
@@ -69,7 +72,13 @@
      */
     @Override
     public NextAction processRequest(Packet request) {
-        Set<QName> misUnderstoodHeaders = getMisUnderstoodHeaders(request.getMessage().getHeaders(),roles, handlerKnownHeaders);
+        Set<QName> misUnderstoodHeaders=null;
+        lock.lock();
+        try{
+            misUnderstoodHeaders = getMisUnderstoodHeaders(request.getMessage().getHeaders(),roles, handlerKnownHeaders);
+        } finally {
+            lock.unlock();
+        }
         if((misUnderstoodHeaders == null)  || misUnderstoodHeaders.isEmpty()) {
             return doInvoke(super.next, request);
         }