CVE-2026-62295: Hapifhir ca.uhn.hapi.fhir:org.hl7.fhir.r5

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

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.

Affected products

• Hapifhir ca.uhn.hapi.fhir:org.hl7.fhir.r5: before 6.9.11 (fixed in 6.9.11)
• Hapifhir ca.uhn.hapi.fhir:org.hl7.fhir.utilities: before 6.9.11 (fixed in 6.9.11)
• Hapifhir ca.uhn.hapi.fhir:org.hl7.fhir.validation: before 6.9.11 (fixed in 6.9.11)
• Hapifhir ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli: before 6.9.11 (fixed in 6.9.11)
• Hapifhir org.hl7.fhir.core: before 6.9.11 (fixed in 6.9.11)

Published 2026-08-07. Last modified 2026-09-09.