    private PropPatchParseResult parseContent( byte[] arr ) throws IOException, SAXException {
        if( arr.length > 0 ) {
            log.debug( "processing content" );
            ByteArrayInputStream bin = new ByteArrayInputStream( arr );
            XMLReader reader = XMLReaderFactory.createXMLReader();
			reader.setFeature("http://xml.org/sax/features/external-parameter-entities", false);
			// https://www.owasp.org/index.php/XML_External_Entity_%28XXE%29_Processing
			reader.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true);
			reader.setFeature("http://xml.org/sax/features/external-general-entities", false);

            PropPatchSaxHandler handler = new PropPatchSaxHandler();
            reader.setContentHandler( handler );
            reader.parse( new InputSource( bin ) );
            log.debug( "toset: " + handler.getAttributesToSet().size());
            return new PropPatchParseResult( handler.getAttributesToSet(), handler.getAttributesToRemove().keySet() );
        } else {
            log.debug( "empty content" );
            return new PropPatchParseResult( new HashMap<QName, String>(), new HashSet<QName>() );
        }

    }

The software processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.