CVE-2026-49485 HAPI FHIR: ReDoS via FHIRPath matches()/replaceMatches() in FHIR Validator HTTP Endpoint

What is CVE-2026-49485?

CVE-2026-49485 is a high-severity denial of service vulnerability in hapifhir org.hl7.fhir.core, published on 17 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

HAPI FHIR is a complete implementation of the HL7 FHIR standard for healthcare interoperability in Java. Prior to 6.9.9 and 6.9.4.2, all implementations of FHIRPathEngine accept arbitrary FHIRPath expressions and evaluate them without input validation, and the FHIRPath functions matches(), matchesFull(), and replaceMatches() pass user-controlled regular expressions to Java's Pattern.compile() and String.replaceAll() through an incomplete timeout utility. An attacker can send a resource containing an evil regex pattern that causes catastrophic backtracking, exhausting CPU resources and causing denial of service in the FHIR Validator HTTP endpoint and affected org.hl7.fhir.* modules. This issue is fixed in versions 6.9.9 and 6.9.4.2.

Weakness: CWE-400, CWE-1333

Which versions are affected by CVE-2026-49485?

32 open source packages ship an affected version, including ca.uhn.hapi.fhir:org.hl7.fhir.dstu2, ca.uhn.hapi.fhir:org.hl7.fhir.dstu2016may and ca.uhn.hapi.fhir:org.hl7.fhir.dstu3.

How do I fix CVE-2026-49485?

Upgrade ca.uhn.hapi.fhir:org.hl7.fhir.dstu2 to a fixed version for your release line: 6.9.4.2 or 6.9.9.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-49485 being exploited?

There is no known exploitation of CVE-2026-49485 in the wild and no public exploit code.

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-7cmj-v6x8-frvv, ROOT-APP-MAVEN-CVE-2026-49485.