XXE vulnerability in XSLT parsing in `org.hl7.fhir.core`

Summary

XSLT parsing performed by various components are vulnerable to XML external entity injections. A processed XML file with a malicious DTD tag ( ]> 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.

Details

This is related to https://github.com/hapifhir/org.hl7.fhir.core/security/advisories/GHSA-6cr6-ph3p-f5rf, in which its fix ( https://github.com/hapifhir/org.hl7.fhir.core/issues/1571, https://github.com/hapifhir/org.hl7.fhir.core/pull/1717) was incomplete.

References

https://cwe.mitre.org/data/definitions/611.html
https://cheatsheetseries.owasp.org/cheatsheets/XML_External_Entity_Prevention_Cheat_Sheet.html#jaxp-documentbuilderfactory-saxparserfactory-and-dom4j