How to disable DTD fetching using JAXB2.0
Below is sample code that demonstrates how to get a JAXB (JSR-222) implementation to use your SAX parser:
import java.io.FileReader;
import javax.xml.XMLConstants;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Unmarshaller;
import javax.xml.parsers.SAXParserFactory;
import javax.xml.transform.sax.SAXSource;
import org.xml.sax.InputSource;
import org.xml.sax.XMLReader;
public class Demo {
public static void main(String[] args) throws Exception {
JAXBContext jc = JAXBContext.newInstance(Foo.class);
SAXParserFactory spf = SAXParserFactory.newInstance();
spf.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true);
XMLReader xmlReader = spf.newSAXParser().getXMLReader();
InputSource inputSource = new InputSource(new FileReader("input.xml"));
SAXSource source = new SAXSource(xmlReader, inputSource);
Unmarshaller unmarshaller = jc.createUnmarshaller();
Foo foo = (Foo) unmarshaller.unmarshal(source);
System.out.println(foo.getValue());
}
}
Building on the answers from @blaise-doughan and @aerobiotic, here is a solution that worked for me:
import java.io.FileReader;
import javax.xml.XMLConstants;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Unmarshaller;
import javax.xml.parsers.SAXParserFactory;
import javax.xml.transform.sax.SAXSource;
import org.xml.sax.InputSource;
import org.xml.sax.XMLReader;
public class Demo2 {
public static void main(String[] args) throws Exception {
JAXBContext jc = JAXBContext.newInstance(MyBean.class);
SAXParserFactory spf = SAXParserFactory.newInstance();
spf.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
spf.setFeature("http://xml.org/sax/features/validation", false);
XMLReader xmlReader = spf.newSAXParser().getXMLReader();
InputSource inputSource = new InputSource(
new FileReader("myfile.xml"));
SAXSource source = new SAXSource(xmlReader, inputSource);
Unmarshaller unmarshaller = jc.createUnmarshaller();
MyBean foo = (MyBean) unmarshaller.unmarshal(source);
}
}
In answer to the question "How to disable DTD fetching using JAXB2.0".
@sameer-puri links to https://cheatsheetseries.owasp.org/cheatsheets/XML_External_Entity_Prevention_Cheat_Sheet.html#SAXTransformerFactory which answers the question as follows:
JAXB Unmarshaller
Since a javax.xml.bind.Unmarshaller parses XML and does not support any flags for disabling XXE, it's imperative to parse the untrusted XML through a configurable secure parser first, generate a source object as a result, and pass the source object to the Unmarshaller. For example:
//Disable XXE
SAXParserFactory spf = SAXParserFactory.newInstance();
spf.setFeature("http://xml.org/sax/features/external-general-entities", false);
spf.setFeature("http://xml.org/sax/features/external-parameter-entities", false);
spf.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
//Do unmarshall operation
Source xmlSource = new SAXSource(spf.newSAXParser().getXMLReader(),
new InputSource(new StringReader(xml)));
JAXBContext jc = JAXBContext.newInstance(Object.class);
Unmarshaller um = jc.createUnmarshaller();
um.unmarshal(xmlSource);