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Fencer Intel
high 7.5

CVE-2026-62295 json

HAPI FHIR: JSON utility parser unbounded recursion causes StackOverflow denial of service

published 3mo ago modified 2mo ago also EUVD-2026-54639

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, the JSON utility parser in org.hl7.fhir.utilities.json.parser.JsonParser enforces no maximum nesting depth for arrays or objects. As a result, a small but deeply nested, syntactically valid FHIR JSON document can trigger unbounded readArray() or readObject() recursion, raising a StackOverflowError before structural validation runs. An attacker who can submit JSON resources for validation can thus crash the request thread, and services that do not isolate StackOverflowError safely may experience worker loss or process instability — a denial-of-service condition. 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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CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
2mo 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-2cq7-hg49-56gc 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.