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Fencer Intel
high 7.5

CVE-2026-62296 json

HAPI FHIR: XHTML narrative parser unbounded recursion causes StackOverflow denial of service

published 3mo ago modified 2mo ago also EUVD-2026-54643

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

HAPI FHIR is a complete implementation of the HL7 FHIR standard for healthcare interoperability in Java. Prior to 6.9.11, XhtmlParser.java imposes no maximum element nesting depth, so a deeply nested text.div narrative triggers unbounded recursion between parseElementInner() and parseElement(), raising a StackOverflowError. An attacker who can submit FHIR resources containing such narratives can thus crash a parsing or validation worker thread, affecting validator services and any application that parses attacker-supplied FHIR JSON or XML. This issue is fixed in version 6.9.11.

Patch / fix

  • ca.uhn.hapi.fhir org.hl7.fhir.core 6.9.11
  • hapifhir hl7_fhir_core 6.9.11

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-62296 updated cvss 7.5

ca.uhn.hapi.fhir/hapi-fhir-base: HAPI FHIR: Denial of Service via unbounded recursion in XHTML narrative parser

  • Red Hat build of Apache Camel 4 for Quarkus 3 hapi-fhir-base 8.6.5
    affected: workaround, no fix available
  • Red Hat Build of Apache Camel 4.18 for Quarkus 3.33
    fixed: vendor fix RHSA-2026:54776
  • Red Hat JBoss Enterprise Application Platform Expansion Pack hapi-fhir-base 8.6.5
    not affected: component not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
3mo ago

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/hapifhir/org.hl7.fhir.core/security/advisories/GHSA-5v24-q6x8-hc38 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • hapifhir org.hl7.fhir.core
  • hapifhir ca.uhn.hapi.fhir:org.hl7.fhir.r5
  • hapifhir ca.uhn.hapi.fhir:org.hl7.fhir.utilities
  • hapifhir ca.uhn.hapi.fhir:org.hl7.fhir.validation
  • hapifhir ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli

Classification

Weakness
  • CWE-20 Improper Input Validation
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-674 Uncontrolled Recursion

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.