CVE-2026-34361 — org.hl7.fhir.validation
CRITICALCVE-2026-34361 is a critical-severity (CVSS 9.3) CWE-552 vulnerability in ca.uhn.hapi.fhir:org.hl7.fhir.validation. A fix is available for ca.uhn.hapi.fhir:org.hl7.fhir.validation — see the affected versions and patch details below.
HAPI FHIR: Unauthenticated SSRF via /loadIG Chains with startsWith() Credential Leak for Authentication Token Theft
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-34361.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-34361 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,333 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
ca.uhn.hapi.fhir:org.hl7.fhir.validationReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
HAPI FHIR is a complete implementation of the HL7 FHIR standard for healthcare interoperability in Java. Prior to version 6.9.4, the FHIR Validator HTTP service exposes an unauthenticated "/loadIG" endpoint that makes outbound HTTP requests to attacker-controlled URLs. Combined with a startsWith() URL prefix matching flaw in the credential provider (ManagedWebAccessUtils.getServer()), an attacker can steal authentication tokens (Bearer, Basic, API keys) configured for legitimate FHIR servers by registering a domain that prefix-matches a configured server URL. This issue has been patched in version 6.9.4.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | ca.uhn.hapi.fhir:org.hl7.fhir.validation | all versions | 6.9.4ca.uhn.hapi.fhir:org.hl7.fhir.validation:6.9.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ca.uhn.hapi.fhir:org.hl7.fhir.validation, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update ca.uhn.hapi.fhir:org.hl7.fhir.validation to 6.9.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34361 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-34361 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-34361. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-34361 in your dependencies?
O3 Security finds CVE-2026-34361 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.