Sandbox::https://github.com/apache/activemq/pull/2635

garydgregory · 2026-10-04T13:35:13Z

Harden XML calls with Apache Commons Secure XML

See also:

Test reliability PR Fix DiscoveryTransportBrokerTest on local macOS #2636
Test reliability PR Start the JMS listener container in AMQFailoverIssue #2637
Test reliability PR Isolate persistence directories in durable subscription tests #2638

In addition,remove "disallow-doctype-decl". Chances are the motivation behind the setting is the same as with Tika: This is not about banning DOCTYPE, just preventing XXE injection.

mattrpav · 2026-10-04T16:32:17Z

Hi @garydgregory

thank you for the PR. Can you share a bit what the advantages are of using this library?

garydgregory · 2026-10-04T16:48:37Z

Hi @mattrpav CC @ppkarwasz

Commons Secure XML is a tiny library that:

Prevents XXE Attacks: It disables external entity resolution, blocking XML External Entity (XXE) vulnerabilities that lead to data exposure.
Prevents Billion Laughs Attacks: It restricts recursive entity expansion, preventing denial-of-service (DoS) attempts.
Configures standard XML parsers with safe, restrictive settings out of the box.
Eliminates manual, error-prone security configuration of DocumentBuilderFactory, SAXParserFactory, TransformerFactory, and so on

HTH!

garydgregory · 2026-10-04T17:06:44Z

Oh, another use case is (like me) when you offer an option to embedded AMQ, AMQ is not in full control of the classpath. When the JRE resolves the JAXP implementation, you may get implementation dependent issues. We talk about this in the introduction in https://commons.apache.org/proper/commons-secure-xml/apidocs/index.html#tldr if you care for the details.

ppkarwasz · 2026-10-04T17:27:15Z

-        trySetFeature(builderFactory,"http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
-
-        return builderFactory;
+        return SecureDocumentBuilderFactory.newInstance();


What about inlinining this method and deprecating this class?

This method has only two callers and both could just use newNSDocumentBuilder that we are about to be introduced in version 1.1.0.

A small difference in the two callers would need to be settled:

RuntimeConfigurationBroker#loadConfiguration uses a namepace-aware parser and retrieves the broker element via:
doc.getElementsByTagNameNS("*","broker").item(0);

CreateCommand#copyActivemqConf uses a namespace-unaware parser and retrieves the same broker element via XPath.

I think both could use a namespace-aware parser

I implemented @ppkarwasz 's suggestion in commit 6264883.

ppkarwasz · 2026-10-04T18:15:12Z

Prevents XXE Attacks: It disables external entity resolution, blocking XML External Entity (XXE) vulnerabilities that lead to data exposure.

And most importantly, this prevents reports of XXE vulnerabilities. As far as I can tell, you only use XML to parse trusted configuration file, which makes all those reports moot, yet you had to harden your parsers for some reason…

Using Commons Secure XML, you can keep your XML code as simple as possible and at the same time reject all XXE reports.

ppkarwasz · 2026-10-04T20:13:28Z

+                DocumentBuilderFactory dbf = SecureDocumentBuilderFactory.newNSInstance();
                dbf.setNamespaceAware(true);

                DocumentBuilder db = dbf.newDocumentBuilder();
                Document doc = db.parse(configToMonitor.getInputStream());


What about upgrading to 1.1.0? All this could collapse to:

Document doc = SecureDocumentBuilderFactory.newNSDocumentBuilder().parse(configToMonitor.getInputStream());

Version 1.1.0 will be available tomorrow evening after 11 PM EDT. I will update the PR then, or create a new one.

ppkarwasz · 2026-10-04T20:26:29Z

-        DocumentBuilder builder = XmlFactories.getSafeDocumentBuilderFactory().newDocumentBuilder();
+        DocumentBuilder builder = SecureDocumentBuilderFactory.newNSInstance().newDocumentBuilder();
        Element docElem = builder.parse(src).getDocumentElement();

-        XPath xpath = XPathFactory.newInstance().newXPath();
+        XPath xpath = SecureXPathFactory.newInstance().newXPath();
        Attr brokerNameAttr = (Attr) xpath.evaluate(DEFAULT_BROKERNAME_XPATH, docElem, XPathConstants.NODE);


This will create a problem with namespaces: the XPath used is /beans/broker/@brokerName, but both beans and broker have a namespace, so the XPath will not find anything with a namespace sensitive parser.

I see a couple of solutions:

Use newInstance() instead of newNSInstance(), but this means this path can not upgrade to newNSDocumentBuilder().

Change the XPath expression to /*[local-name()='beans'/*[local-name()='broker']/@brokerName.

Or use DOM to find the attribute:

Element brokerElement = (Element) docElem.getElementsByTagNameNS("*", "broker").item(0); Attr brokerNameAttr = brokerElement.getAttributeNodeNS(null, "brokerName");

@ppkarwasz I implemented your suggestion 2 in commit d64bcfd.
I like the XPath approach with namespaces because it is more precise IMO.

Unless I am mistaken, all ActiveMQ configurations need to use namespaces, otherwise Spring will not accept them. Therefore you can also set a NamespaceContext on the XPath (there is a SimpleNamespaceContext in spring-core if you don't want to create your own), bind the namespaces and use something like /b:beans/a:broker/@brokerName.

Hm, that may be the case but it feels like we are entering clean up territory instead of migrating to Commons Secure XML. I'd rather leave that one for the AMQ team and not make this PR more complicated.

Remove setNamespaceAware() no longer needed with SecureDocumentBuilderFactory.newNSInstance().

Spring imports the XML namespace without a schema location. Preload it so the secure resolver does not return an empty document.

Implement the suggestion in apache#2635 (review)

garydgregory added 2 commits October 4, 2026 09:24

Harden XML calls with Apache Commons Secure XML

3d9776b

Harden XML calls with Apache Commons Secure XML

9fb7cc4

In addition,remove "disallow-doctype-decl". Chances are the motivation behind the setting is the same as with Tika: This is not about banning DOCTYPE, just preventing XXE injection.

ppkarwasz reviewed Oct 4, 2026

View reviewed changes

garydgregory changed the title ~~Main commons secure xml~~ Harden XML with Commons Secure XML Oct 4, 2026

Deprecate XmlFactories and inline one-liners

6264883

ppkarwasz reviewed Oct 4, 2026

View reviewed changes

garydgregory added 3 commits October 4, 2026 16:27

Harden XML calls with Apache Commons Secure XML

9856538

Remove setNamespaceAware() no longer needed with SecureDocumentBuilderFactory.newNSInstance().

Harden XML calls with Apache Commons Secure XML

86f23d0

Spring imports the XML namespace without a schema location. Preload it so the secure resolver does not return an empty document.

Harden XML calls with Apache Commons Secure XML

d64bcfd

Implement the suggestion in apache#2635 (review)

mattrpav added this to Apache ActiveMQ Backlog Oct 6, 2026

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