COMMONSXML-6: XMLInputFactory: capability-driven hardening - #12
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garydgregory merged 2 commits intoJul 5, 2026
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Replace the per-implementation class-name dispatch for StAX with a single capability-driven recipe, mirroring the DocumentBuilderFactory and SAXParserFactory rework. A new StaxHardener consolidates the JDK Zephyr and Woodstox recipes into one pass that probes which properties each factory accepts and adapts: - Limits are applied best-effort by Limits.tryApply(XMLInputFactory), which sets both the JDK URL limit properties and the Woodstox com.ctc.wstx.* properties; each implementation honours its own and rejects the other's. - The external DTD subset is skipped via Zephyr's ignore-external-dtd (best-effort) so a DOCTYPE-only document still parses without a fetch attempt. - External entities are denied through resolvers, leaving the standard SUPPORT_DTD / IS_SUPPORTING_EXTERNAL_ENTITIES defaults untouched. Woodstox exposes fine-grained hooks (dtdResolver, entityResolver, undeclaredEntityResolver), so when all three apply the factory is Woodstox; any factory that does not accept that trio (the JDK Zephyr, or an unrecognized implementation) instead gets a single deny-all XMLResolver via setXMLResolver. JaxpSetters gains trySetProperty(XMLInputFactory) and setOptionalProperty(XMLInputFactory). Limits.tryApply(XMLInputFactory) replaces applyToJdkStax and applyToWoodstox. WoodstoxProvider and StockJdkProvider.configure(XMLInputFactory) are removed; XmlFactories.newXMLInputFactory() routes through StaxHardener. The DTD_SUBSET_ONLY resolver moves to StaxHardener, and its SpotBugs known-null exclusion moves with it. An implementation is no longer rejected for being unrecognized: it is hardened best-effort, with the deny-all XMLResolver as the fallback. The throw-on-external -entity behaviour of both bundled parsers is preserved, so the StAX attack tests are unchanged. Assisted-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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The Jira ticket is COMMONSXML-6 |
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Hi @ppkarwasz |
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I resolved the conflicts in both this and #13. I will also submit one last PR of this series that refactors
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Merged, thank you @ppkarwasz 🚀 |
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@ppkarwasz |
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Applies the COMMONSXML-1 capability-driven approach to the StAX path, replacing the per-implementation class-name dispatch for
XMLInputFactorywith a singleStaxHardener.ACCESS_EXTERNAL_*, soStaxHardener.hardenconsolidates the JDK Zephyr and Woodstox recipes into one pass: apply limits and Zephyrignore-external-dtdbest-effort, try the Woodstox resolver trio, and fall back to a single deny-allXMLResolverwhen that trio is not accepted.SUPPORT_DTD/IS_SUPPORTING_EXTERNAL_ENTITIESdefaults untouched, so both bundled parsers keep their original throw-on-external-entity behavior.Limits.tryApply(XMLInputFactory)replacesapplyToJdkStax/applyToWoodstox;JaxpSettersgainstrySetProperty(XMLInputFactory)andsetOptionalProperty(XMLInputFactory).WoodstoxProviderandStockJdkProvider.configure(XMLInputFactory)are removed;XmlFactories.newXMLInputFactory()routes throughStaxHardener. TheDTD_SUBSET_ONLYresolver and its SpotBugs known-null exclusion move with it.Behaviour: an unrecognized StAX implementation is now hardened best-effort (deny-all
XMLResolver) instead of being rejected; on such an implementation that fallback also denies the external subset, so a DOCTYPE-only document may fail (fail-closed). The StAX attack tests are unchanged.mvn verifygreen across the stock JDK (Zephyr) and Woodstox profiles.