CVE-2026-34360

FHIR Validator: Unauthenticated Blind SSRF via /loadIG Endpoint Enables Internal Network Probing

An unauthenticated attacker with network access to the FHIR Validator HTTP service can:

• Probe internal network services, differentiate open/closed ports and reachable/unreachable hosts via error message analysis (connection refused vs. timeout vs. content parse errors)
• Access cloud metadata endpoints, reach AWS/GCP/Azure instance metadata services (169.254.169.254) from the validator's network position
• Map internal network topology, systematically enumerate internal hosts and services
• Bypass domain restrictions via redirects, even if allowedDomains is configured, redirect following does not re-validate targets
• Amplify reconnaissance, each /loadIG call with explore=true generates multiple outbound requests (package.tgz, JSON, XML variants)

This is a blind SSRF, the fetched content is not directly returned. Impact is limited to network probing and error-based information leakage rather than full content exfiltration.

Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.

CVE-2026-34360 has a CVSS score of 5.8 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (6.9.4); upgrading removes the vulnerable code path.

Kodem intelligence

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1. What is CVE-2026-34360? CVE-2026-34360 is a medium-severity server-side request forgery (SSRF) vulnerability in ca.uhn.hapi.fhir:org.hl7.fhir.core (maven), affecting versions < 6.9.4. It is fixed in 6.9.4. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
2. How severe is CVE-2026-34360? CVE-2026-34360 has a CVSS score of 5.8 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of ca.uhn.hapi.fhir:org.hl7.fhir.core are affected by CVE-2026-34360? ca.uhn.hapi.fhir:org.hl7.fhir.core (maven) versions < 6.9.4 is affected.
4. Is there a fix for CVE-2026-34360? Yes. CVE-2026-34360 is fixed in 6.9.4. Upgrade to this version or later.
5. Is CVE-2026-34360 exploitable, and should I be worried? Whether CVE-2026-34360 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-34360 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-34360? Upgrade ca.uhn.hapi.fhir:org.hl7.fhir.core to 6.9.4 or later.

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