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CVE-2026-55471

Critical Vulnerability: CVE-2026-55471 — hapifhir — hl7_fhir_core

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 reach

Thursday, July 16, 2026hapifhirVulnios Threat Intelligence
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Vulnerability Snapshot

CVE-2026-55471 is rated CRITICAL — exploitation is trivial or already observed in the wild and impact is severe. Patch immediately, not on the next maintenance window.

Affected technology: hl7_fhir_core.

Executive Summary

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.

Why It Matters

CVE-2026-55471 is rated CRITICAL severity, requiring immediate attention from security teams.

CVSS Base Score: 9.1/10

Affected Technologies

Vendors: hapifhir

Products: hl7_fhir_core

🛡️What Defenders Should Check

  • Check if you are affected — Review your asset inventory for products listed in CVE-2026-55471.
  • Apply available patches — Visit vendor advisories for the latest security updates.
  • Monitor for exploitation — Check your SIEM/IDS logs for related indicators.

    • Use Vulnios to continuously monitor your exposure to CVE-2026-55471 and similar vulnerabilities.

    References & Sources

  • https://github.com/hapifhir/org.hl7.fhir.core/commit/01ca2ecdefec9b33204d2495fe78af8c0dc52298
  • https://github.com/hapifhir/org.hl7.fhir.core/releases/tag/6.9.10
  • https://github.com/hapifhir/org.hl7.fhir.core/security/advisories/GHSA-2f55-g35j-5jmf
  • https://github.com/hapifhir/org.hl7.fhir.core/security/advisories/GHSA-2f55-g35j-5jmf

    • How Vulnios Detects This

    Vulnios scans for this vulnerability using Nuclei templates that probe live HTTP surfaces for the published exploit pattern. Run a scan against your environment to see whether you are exposed; findings are linked back to the original CVE record so triage starts with the patch path already known.

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    Affected Products

    hl7_fhir_core

    Sources

    Related Threat Alerts

    Frequently Asked Questions

    What is CVE-2026-55471?

    CVE-2026-55471 is a critical-severity vulnerability tracked under the Common Vulnerabilities and Exposures program. 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 instantiate

    Am I affected?

    Check whether your environment runs hl7_fhir_core. If you operate any of those, treat yourself as in scope until you have evidence otherwise. A Vulnios scan will identify the exact assets carrying the affected version.

    How urgent is the response?

    Critical: do not wait for your normal patch cycle. Verify exposure today, apply the vendor patch immediately, and add detection rules for any post-exploit indicators.

    How do I remediate?

    Apply the vendor patch listed in the upstream advisory linked under Sources. If the patch is not yet available, follow the vendor-supplied workaround (often a config flag or feature disable) and add detections for the published exploit pattern in your SIEM. Re-scan after the patch lands to confirm the finding clears.

    Where can I track exploitation activity?

    Watch CISA's Known Exploited Vulnerabilities catalog for CVE-2026-55471. Cross-reference with public exploit databases and your own SIEM/IDS for indicator-of-compromise patterns. Vulnios tracks KEV status automatically and surfaces it on the asset findings view.

    How does Vulnios help with this?

    Vulnios continuously cross-references your asset inventory against the live CVE feed (NVD, vendor advisories, CISA KEV, and curated OSINT). When a new CVE matches your environment, you get a prioritized finding with the severity, KEV status, exploit-prediction (EPSS), and a direct path to the vendor patch. You can start a free scan from the homepage.

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