CVE-2026-61586

Copernik XML Factory through `0.1.1`, when running on its stock JDK provider, does not block XInclude resource resolution after an application enables XInclude on a factory returned by `XmlFactories.newDocumentBuilderFactory()` or `XmlFactories.newSAXParserFactory()`, or on an `XMLReader` passed through `XmlFactories.harden()`. The library's documented guarantee that XInclude resolution stays disabled therefore does not hold on that provider. An application that parses untrusted XML in this configuration can be made to resolve `xi:include` references, allowing an attacker to read local files (information disclosure) or, through `http` hrefs, reach internal network endpoints (SSRF). All of the following conditions must hold for an application to be affected: - it obtains a factory from `XmlFactories.newDocumentBuilderFactory()` or `XmlFactories.newSAXParserFactory()`, or hardens an externally obtained `XMLReader` with `XmlFactories.harden()`; - the stock JDK provider is in effect, that is, Apache Xerces is not on the classpath; - XInclude is enabled, by calling `setXIncludeAware(true)` or the equivalent reader feature; - it parses XML from an untrusted source. The Xerces provider (selected when Xerces is on the classpath) and the Android provider are not affected. Applications are advised to upgrade to `0.1.2`, which fixes the defect. As a workaround add Apache Xerces (`xercesImpl`) to the classpath so the library selects its unaffected Xerces provider. ### Acknowledgements The maintainer thank the following people for finding, reporting, and helping to remediate this issue: - Finders: Ta Duc Thien and Duc Anh Nguyen (Danzation) - Remediation developer: Ta Duc Thien - Tooling: Claude Code (Anthropic), Claude Opus 4.8

No confirmed active exploitation of CVE-2026-61586 has been reported, but organizations should still patch proactively.

Update to patched version: Anthropic Python 0.1.2.

No CVSS score has been assigned yet.