HAPI FHIR: XXE in XsltUtilities.saxonTransform via unhardened Saxon TransformerFactory

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

9.2 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N · score source

EPSS

• CVE-2026-55471: 0.57% estimated exploitation activity in the next 30 days; percentile 47.17 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary org.hl7.fhir.utilities.XsltUtilities exposes two parallel families of XSLT transform helpers. The transform(...) overloads obtain their TransformerFactory from the project's hardened helper XMLUtil.newXXEProtectedTransformerFactory() (which sets ACCESSEXTERNALDTD="" and ACCESSEXTERNALSTYLESHEET=""). The sibling saxonTransform(...) overloads instead instantiate a bare new net.sf.saxon.TransformerFactoryImpl() with no external-access restriction. A document transformed through any saxonTransform(...) overload is parsed with external general entities and external DTD/parameter entities enabled, so an attacker who controls (or can MITM) the transformed XML obtains XML External Entity injection: local file disclosure and blind XXE / SSRF to arbitrary URLs reachable from the host. XMLUtil documents that its protected factory "should be the only place where TransformerFactory is instantiated in this project". The saxonTransform overloads violate that contract while their same-file…

Published by the source

17 Jun 2026, 18:47 UTC

Last modified by the source

17 Jun 2026, 18:47 UTC

Source last checked

26 Oct 2026, 16:53 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-2f55-g35j-5jmf

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# Patch Next advisory brief: CVE-2026-55471

Advisory: HAPI FHIR: XXE in XsltUtilities.saxonTransform via unhardened Saxon TransformerFactory
IDs: CVE-2026-55471, GHSA-2f55-g35j-5jmf
Record: https://patchnext.com/advisories/cve-2026-55471 (revision 1, source checked 26 Oct 2026, 16:53 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: ca.uhn.hapi.fhir:org.hl7.fhir.utilities 6.9.10. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven ca.uhn.hapi.fhir:org.hl7.fhir.utilities: affected <= 6.9.9; fixed in 6.9.10

## Suggested inspection (read-only)
- Maven ca.uhn.hapi.fhir:org.hl7.fhir.utilities: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on ca.uhn.hapi.fhir:org.hl7.fhir.utilities.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-2f55-g35j-5jmf (GitHub-reviewed advisory GHSA-2f55-g35j-5jmf lists affected ranges: Maven ca.uhn.hapi.fhir:org.hl7.fhir.utilities >=0 <=6.9.9)

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