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security: disable XML DTD processing in XmlPullParser to prevent XXE #2183

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security: disable XML DTD processing in XmlPullParser to prevent XXE #2183

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8 changes: 7 additions & 1 deletion google-http-client-xml/src/main/java/com/google/api/client/xml/Xml.java
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Original file line number Diff line number Diff line change
Expand Up @@ -87,7 +87,13 @@ public static XmlSerializer createSerializer() {

/** Returns a new XML pull parser. */
public static XmlPullParser createParser() throws XmlPullParserException {
return getParserFactory().newPullParser();
XmlPullParser parser = getParserFactory().newPullParser();
try {
parser.setFeature(XmlPullParser.FEATURE_PROCESS_DOCDECL, false);
} catch (XmlPullParserException e) {
// Ignore if the feature is not supported
}
return parser;
}

/**
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23 changes: 23 additions & 0 deletions google-http-client-xml/src/test/java/com/google/api/client/xml/XmlTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@
import com.google.api.client.util.ArrayMap;
import com.google.api.client.util.Key;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.Collection;
Expand All @@ -31,6 +32,7 @@
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlSerializer;

/**
Expand Down Expand Up @@ -621,4 +623,25 @@ private static class AllType {
@Key public String[] stringArray;
@Key public List<Integer> integerCollection;
}

@Test
public void testCreateParser_disablesDocDecl() throws Exception {
XmlPullParser parser = Xml.createParser();
String xmlWithDtd = "<?xml version=\"1.0\"?>\n"
+ "<!DOCTYPE any [\n"
+ " <!ENTITY xxe \"injected\">\n"
+ "]>\n"
+ "<any>&xxe;</any>";
parser.setInput(new StringReader(xmlWithDtd));
try {
SimpleTypeString xml = new SimpleTypeString();
XmlNamespaceDictionary namespaceDictionary = new XmlNamespaceDictionary().set("", "");
Xml.parseElement(parser, xml, namespaceDictionary, null);
if (xml.value != null) {
assertTrue(xml.value.isEmpty() || xml.value.equals("&xxe;"));
}
} catch (XmlPullParserException | IOException e) {
// Expected exception if the parser fails on DOCDECL
}
}
}
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