---
title: "CVE-2026-34361: FHIR Validator HTTP service has SSRF via /loadIG Chains with startsWith() Credential Leak for Authentication Token Theft"
url: https://erroneo.us/security/cve/CVE-2026-34361/
description: "CVE-2026-34361 (ca.uhn.hapi.fhir:org.hl7.fhir.validation (Maven)): HAPI FHIR is a complete implementation of the HL7 FHIR standard for healthcare…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-03-31
date_modified: 2026-03-31
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-34361"
kev: false
cvss: 9.3
epss: 0.00422
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-34361: FHIR Validator HTTP service has SSRF via /loadIG Chains with startsWith() Credential Leak for Authentication Token Theft

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.4% , percentile 35: FIRST’s model estimates a 0.4% chance of exploitation activity in the next 30 days, higher than 35% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes ca.uhn.hapi.fhir:org.hl7.fhir.validation (Maven) < 6.9.4, fixed in 6.9.4 . Check your lockfile, including transitive dependencies.

## What it is

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

- Maven `ca.uhn.hapi.fhir:org.hl7.fhir.validation` < 6.9.4 → fixed: 6.9.4

## Affected products (CVE record)

- hapifhir org.hl7.fhir.core: < 6.9.4

## Severity

- GitHub_M CVSS 3.1: 9.3 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N`
- GitHub CVSS 3.1: 9.3 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact partial .
- FIRST EPSS (model of 2026-10-21): 0.42% probability of exploitation activity in the next 30 days; percentile 35.

## Sources

- [GitHub Advisory GHSA-vr79-8m62-wh98](https://github.com/advisories/GHSA-vr79-8m62-wh98)
- [CVE.org record CVE-2026-34361](https://www.cve.org/CVERecord?id=CVE-2026-34361)
- [NVD entry CVE-2026-34361](https://nvd.nist.gov/vuln/detail/CVE-2026-34361)
- [github.com](https://github.com/hapifhir/org.hl7.fhir.core/security/advisories/GHSA-vr79-8m62-wh98)

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Source page: https://erroneo.us/security/cve/CVE-2026-34361/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt