Java and Xerces: can't find property XMLConstants.ACCESS_EXTERNAL_DTD

Question

I looked for similar posts on this blog, but couldn't find an answer to my question, so I decided to ask for help.

I wrote this simple function in Java:

 public void open(InputStream stream) throws FoliumFatalException {
        try {
            InputSource is = new InputSource(stream);
            DocumentBuilderFactory dfact = DocumentBuilderFactory.newInstance();

//            /* OWASP: inhibit access to External Entities */
            dfact.setAttribute(XMLConstants.ACCESS_EXTERNAL_DTD, ""); 
            dfact.setAttribute(XMLConstants.ACCESS_EXTERNAL_SCHEMA, ""); 

            _doc = dfact.newDocumentBuilder().parse(is);

        } catch (Throwable t) {
            _logger.error(t, t);
            throw new FoliumFatalException("ENG-0017", "Errore di parsing su stream", t);
        }

    }

My goal is applying OWASP standards as exposed here, but I get the following error:

 java.lang.IllegalArgumentException: Property 'http://javax.xml.XMLConstants/property/accessExternalDTD' is not recognized.
java.lang.IllegalArgumentException: Property 'http://javax.xml.XMLConstants/property/accessExternalDTD' is not recognized.
    at org.apache.xerces.jaxp.DocumentBuilderFactoryImpl.setAttribute(Unknown Source) ~[xercesImpl-2.8.0.jar:?]
    at agora.folium.engine.impl.j2ee.FoliumJ2eeXmlParserImpl.open(FoliumJ2eeXmlParserImpl.java:108) [classes/:?]
    at agora.folium.engine.impl.FoliumAbstractEngine.loadServices(FoliumAbstractEngine.java:268) [classes/:?]
    at agora.folium.engine.impl.j2ee.FoliumJ2eeEngineImpl.startup(FoliumJ2eeEngineImpl.java:110) [classes/:?]
    at agora.folium.engine.Folium.startup(Folium.java:258) [classes/:?]
    at agora.folium.control.impl.j2ee.FoliumActionServlet.init(FoliumActionServlet.java:94) [classes/:?]
    at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1230) [catalina.jar:7.0.85]
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1174) [catalina.jar:7.0.85]
    at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1066) [catalina.jar:7.0.85]
    at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5370) [catalina.jar:7.0.85]
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5668) [catalina.jar:7.0.85]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145) [catalina.jar:7.0.85]
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:1015) [catalina.jar:7.0.85]
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:991) [catalina.jar:7.0.85]
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:652) [catalina.jar:7.0.85]
    at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:712) [catalina.jar:7.0.85]
    at org.apache.catalina.startup.HostConfig$DeployDescriptor.run(HostConfig.java:2002) [catalina.jar:7.0.85]
    at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.8.0_141]
    at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_141]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:1.8.0_141]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:1.8.0_141]
    at java.lang.Thread.run(Unknown Source) [?:1.8.0_141]

I'm using Eclipse Oxygen, Tomcat 7 and Java 1.8. Can anyone help me?

Thanks for your support.

user_11271432 · Answer

javax.xml.XMLConstants.ACCESS_EXTERNAL_DTD is defined in JAXP 1.5, but Xerces does not support it. If you can't remove Xerces dependency, you should add another implementation to your classpath before Xerces.

Alternatively, since JDK contains an implementation of Xerces you can configure DocumentBuilderFactory to return the JDK version using System.properties.

System.setProperty("javax.xml.parsers.DocumentBuilderFactory",
        "com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl");

user_2751466 · Answer

The issue is coming due to Xerces/XercesImpl in classpath. Xerces doesn't provide support for ACCESS_EXTERNAL_DTD property.

Solution 1. If possible, remove xerces jar from the class path.

Solution 2. Use JDK default implementation

DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance("com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl", null);

user_5583341 · Answer

Apache Xerces-J 2.12.0 and earlier implement older versions of JAXP that do not support either of the properties that you are trying to set. To block access to external entities, you could write an EntityResolver (that always throws a SAXException) and register that EntityResolver with the DocumentBuilder. See documentation here [1].

[1] http://xerces.apache.org/xerces2-j/javadocs/api/javax/xml/parsers/DocumentBuilder.html#setEntityResolver(org.xml.sax.EntityResolver)

user_11066016 · Answer

Our Java project was being built with Maven. As the team decided to integrate SonarQube in the pipeline, we faced something similar. "SonarQube doesn't run your tests or generate reports. It only imports pre-generated reports" (more on that here). In the case of Java/Kotlin/Scala/JVM, SonarQube needs some "JaCoCo XML coverage report". So, we had to add a dependency to our pom.xml:


  org.jacoco
  jacoco-maven-plugin
  ${jacoco.version}

After some tweaking, we had it all up and running. But some tests were failing with "java.lang.IllegalArgumentException: Property 'http://javax.xml.XMLConstants/property/accessExternalDTD' is not recognized. at org.apache.xerces.jaxp.DocumentBuilderFactoryImpl.setAttribute(Unknown Source)...".

Long story short, the solution was to leave xerces out of the picture, as already stated in other answers:


  org.jacoco
  jacoco-maven-plugin
  ${jacoco.version}
  
    
      xerces
      xercesImpl

Java and Xerces: can't find property XMLConstants.ACCESS_EXTERNAL_DTD

4 Answers