Resource exhaustion in Hapifhir Ca.uhn.hapi.fhir:org.hl7.fhir.r5

CVE-2026-62296

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.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

EPSS: 0.003 (27.1th percentile) — read the EPSS interpretation.