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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service
CVSS Vector v3.1
Weakness Type (CWE)
Vulnerable Products
hapifhir:ca.uhn.hapi.fhir:org.hl7.fhir.validation
hapifhir:ca.uhn.hapi.fhir:org.hl7.fhir.utilities
hapifhir:ca.uhn.hapi.fhir:org.hl7.fhir.r5
hapifhir:org.hl7.fhir.core
hapifhir:ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli