CVE-2026-55471 [CRITICAL] – HAPI FHIR is a complete implementation of the HL7 FHIR standard for healthcare interoperab

HAPI FHIR is a complete implementation of the HL7 FHIR standard for healthcare interoperability in Java. Prior to 6.9.10, org.hl7.fhir.utilities.XsltUtilities saxonTransform(…) overloads instantiated a bare net.sf.saxon.TransformerFactoryImpl() without ACCESS_EXTERNAL_DTD or ACCESS_EXTERNAL_STYLESHEET restrictions, allowing an attacker who controls or can tamper with transformed XML to trigger XML External Entity injection for local file disclosure and blind XXE or SSRF to arbitrary URLs reachable from the host. This issue is fixed in version 6.9.10.