--- old/modules/javafx.web/src/main/native/Source/WebCore/bridge/jni/jsc/BridgeUtils.cpp	2017-10-17 17:12:36.436630200 +0530
+++ new/modules/javafx.web/src/main/native/Source/WebCore/bridge/jni/jsc/BridgeUtils.cpp	2017-10-17 17:12:35.367923000 +0530
@@ -120,6 +120,7 @@
     if (val == NULL)
         return JSValueMakeNull(ctx);
     JSC::ExecState* exec = toJS(ctx);
+    JSC::JSLockHolder lock(exec);
 
     jclass clJSObject = getJSObjectClass(env);
     if (env->IsInstanceOf(val, clJSObject)) {
@@ -274,6 +275,7 @@
             if (rootObject) {
                 context = WebCore::getGlobalContext(&frame->script());
                 JSC::ExecState* exec = toJS(context);
+                JSC::JSLockHolder lock(exec);
 
                 object = const_cast<JSObjectRef>(toRef(exec,
                     (peer_type == com_sun_webkit_dom_JSObject_JS_DOM_WINDOW_OBJECT)