High [CVE-2026-55470] ca.uhn.hapi.fhir/org.hl7.fhir.validation.cli: HAPI FHIR: Denial of Service via Regular Expression Backtracking in DSTU2 Module
This high-severity Red Hat Linux advisory covers CVE-2026-55470 affecting Red Hat Build of Apache Camel 4.18 for Quarkus 3.33, Red Hat build of Apache Camel 4 for Quarkus 3.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
VulniPulse record published Record updated
Summary
HAPI FHIR is a complete implementation of the HL7 FHIR standard for healthcare interoperability in Java.
Prior to 6.9.10, the fix for CVE-2026-45367 incompletely patched the DSTU2 module, leaving FHIRPathEngine.matches() in org.hl7.fhir.dstu2/utils/FHIRPathEngine.java to call raw String.matches(sw) without RegexTimeout protection while replaceMatches() was updated, allowing an unauthenticated attacker to trigger catastrophic regex backtracking and exhaust server CPU.
This issue is fixed in version 6.9.10. Specifically, the FHIRPathEngine.matches() function in org.hl7.fhir.dstu2 did not include protection against regular expression timeouts.
This allows an unauthenticated attacker to submit a specially crafted FHIRPath expression, triggering catastrophic regular expression (regex) backtracking. The consequence is a Regular Expression Denial of Service (ReDoS), which can exhaust server CPU resources and lead to service disruption.
This flaw is rated as Important because an unauthenticated, remote attacker can exploit an incomplete patch in the HAPI FHIR DSTU2 module.
By submitting a specially crafted FHIRPath expression, an attacker can trigger a Regular Expression Denial of Service (ReDoS) attack, leading to significant resource exhaustion and service unavailability on affected systems. Red Hat severity: Important — CVSS 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
Is CVE-2026-55470 exploited?
No exploitation is reported in the sources VulniPulse tracks: CVE-2026-55470 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.
How do I fix CVE-2026-55470?
Upgrade to a fixed release named by Red Hat:
- 6.9.10
- org.hl7.fhir.dstu2
- RHSA-2026:54776
Confirm against the vendor advisory before you patch.
- < 6.9.10
Official advisory · high-confidence parse· fetched 11 days ago·verify at source
- 6.9.10
- org.hl7.fhir.dstu2
- RHSA-2026:54776
Official advisory · high-confidence parse· fetched 11 days ago·verify at source
Mitigation checklist
- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Official advisory · high-confidence parse· fetched 11 days ago·verify at source
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