HAPI FHIR is a complete implementation of the HL7 FHIR standard for healthcare interoperability in Java. Prior to 6.9.10, the fix for CVE-2026-45367 incompletely patched the DSTU2 module, leaving FHIRPathEngine.matches() in org.hl7.fhir.dstu2/utils/FHIRPathEngine.java to call raw String.matches(sw) without RegexTimeout protection while replaceMatches() was updated, allowing an unauthenticated attacker to trigger catastrophic regex backtracking and exhaust server CPU. This issue is fixed in version 6.9.10.

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 ACCESSEXTERNALDTD or ACCESSEXTERNALSTYLESHEET 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.

HAPI FHIR is a complete implementation of the HL7 FHIR standard for healthcare interoperability in Java. Prior to 6.9.11, the hidden scan command concatenates attacker-controlled Implementation Guide titles, profile titles, and source references into scan.html without escaping in Scanner.java. As a result, a user who scans an attacker-supplied IG/profile and then opens or publishes the generated local/CI HTML report can trigger stored cross-site scripting, executing attacker-controlled JavaScript in the report's browser context. This issue is fixed in version 6.9.11.

HAPI FHIR is a complete implementation of the HL7 FHIR standard for healthcare interoperability in Java. XSLT parsing performed by various components are vulnerable to XML external entity injections. A processed XML file with a malicious DTD tag ( <!DOCTYPE foo [<!ENTITY example SYSTEM "/etc/passwd"> ]> could produce XML containing data from the host system. This impacts use cases where org.hl7.fhir.core is being used to within a host where external clients can submit XML. This is related to GHSA-6cr6-ph3p-f5rf, in which its fix (#1571 & #1717) was incomplete. This issue has been addressed in release version 6.4.0 and all users are advised to upgrade. There are no known workarounds for this vulnerability.