---
id: CVE-2026-81876
title: >-
  HAPI FHIR is a complete implementation of the HL7 FHIR standard for healthcare
  interoperability in Java
summary: >-
  HAPI FHIR is a complete implementation of the HL7 FHIR standard for healthcare
  interoperability in Java. Prior to version 6.9.12, SHCParser in
  org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/SHCParser.java can
  enter an infinit…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-20
  - CWE-400
  - CWE-835
vendor: hapifhir
product: org.hl7.fhir.core
affected:
  - org.hl7.fhir.core < 6.9.12
published: '2026-09-16'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T14:17:32.600'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-81876'
references:
  - url: >-
      https://github.com/hapifhir/org.hl7.fhir.core/commit/d804558bd77372b1629e55a5b901cad3f5134cdc
    label: security-advisories@github.com
  - url: >-
      https://github.com/hapifhir/org.hl7.fhir.core/commit/edd5d8c139e669e39270785f08be7b63aefef24c
    label: security-advisories@github.com
  - url: 'https://github.com/hapifhir/org.hl7.fhir.core/pull/2493'
    label: security-advisories@github.com
  - url: >-
      https://github.com/hapifhir/org.hl7.fhir.core/security/advisories/GHSA-gq9c-wmrm-5hvr
    label: security-advisories@github.com
  - url: >-
      https://github.com/hapifhir/org.hl7.fhir.core/security/advisories/GHSA-gq9c-wmrm-5hvr
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-81876'
  - url: 'https://github.com/advisories/GHSA-gq9c-wmrm-5hvr'
tags:
  - nvd
  - cve.org
  - ghsa
  - maven
ingestedAt: '2026-09-16T19:02:30.724Z'
aliases:
  - GHSA-gq9c-wmrm-5hvr
ecosystem: maven
patched:
  - 'ca.uhn.hapi.fhir:org.hl7.fhir.r5 6.9.12'
  - 'ca.uhn.hapi.fhir:org.hl7.fhir.validation 6.9.12'
  - 'ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli 6.9.12'
epss: 0.0063
epssPercentile: 0.47877
---

## Overview

HAPI FHIR is a complete implementation of the HL7 FHIR standard for healthcare interoperability in Java. Prior to version 6.9.12, SHCParser in org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/SHCParser.java can enter an infinite loop while processing attacker-controlled Smart Health Card JWT content whose header contains zip: "DEF" and whose raw-DEFLATE payload is empty or truncated. SHCParser.decodeJWT() reaches SHCParser.inflate(), where Inflater.inflate() can return zero while Inflater.finished() remains false and Inflater.needsInput() is true. The loop also lacks an Inflater.needsDictionary() termination check, SHCParser.decompress() contains the same zero-progress pattern, and ResourceChecker.java can reach SHC parsing during file-format detection. A malformed validation request can pin a JVM worker thread indefinitely, and concurrent requests can exhaust all validation workers. This issue is fixed in version 6.9.12.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-81876)

Affected packages:

- `ca.uhn.hapi.fhir:org.hl7.fhir.r5 <= 6.9.11`
- `ca.uhn.hapi.fhir:org.hl7.fhir.validation <= 6.9.11`
- `ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli <= 6.9.11`

Patched in:

- `ca.uhn.hapi.fhir:org.hl7.fhir.r5 6.9.12`
- `ca.uhn.hapi.fhir:org.hl7.fhir.validation 6.9.12`
- `ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli 6.9.12`

Source: https://github.com/advisories/GHSA-gq9c-wmrm-5hvr