# CVE-2026-55470: HAPI FHIR ReDoS in DSTU2 FHIRPathEngine

Source: https://junglewise.ai/threats/cve-2026-55470-hapi-fhir-redos-in-dstu2-fhirpathengine  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-08. Updated: 2026-07-08  
License: CC BY 4.0 with a link back

CVE-2026-55470 · Severity: high · CVSS 7.5 · Published 2026-07-08

HAPI FHIR is a Java-based library used by healthcare organizations to exchange and validate medical data. A flaw in its data processing engine allows an unauthenticated attacker to send specially crafted requests that cause the server's processor to become overwhelmed. This can lead to a complete service outage, preventing legitimate users and medical systems from accessing or sharing critical healthcare information.

Technologies: [ca.uhn.hapi.fhir:org.hl7.fhir.convertors (Maven)](https://junglewise.ai/threats/technologies/ca-uhn-hapi-fhir-org-hl7-fhir-convertors), [ca.uhn.hapi.fhir:org.hl7.fhir.dstu2 (Maven)](https://junglewise.ai/threats/technologies/ca-uhn-hapi-fhir-org-hl7-fhir-dstu2), [ca.uhn.hapi.fhir:org.hl7.fhir.validation (Maven)](https://junglewise.ai/threats/technologies/ca-uhn-hapi-fhir-org-hl7-fhir-validation), [ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli (Maven)](https://junglewise.ai/threats/technologies/ca-uhn-hapi-fhir-org-hl7-fhir-validation-cli). Vendors: [Maven](https://junglewise.ai/threats/vendors/maven).

## Quick answers

**Is CVE-2026-55470 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-55470 being exploited in the wild.

**How severe is CVE-2026-55470?** High severity, with a CVSS score of 7.5, published 8 July 2026.

**Which products and versions are affected?** ca.uhn.hapi.fhir:org.hl7.fhir.convertors (Maven) <= 6.9.9, ECOSYSTEM:introduced=0,fixed=6.9.10; ca.uhn.hapi.fhir:org.hl7.fhir.dstu2 (Maven) <= 6.9.9, ECOSYSTEM:introduced=0,fixed=6.9.10; ca.uhn.hapi.fhir:org.hl7.fhir.validation (Maven) <= 6.9.9, ECOSYSTEM:introduced=0,fixed=6.9.10; ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli (Maven) <= 6.9.9, ECOSYSTEM:introduced=0,fixed=6.9.10; and 4 more.

**Is there a fix for CVE-2026-55470?** Yes. ca.uhn.hapi.fhir:org.hl7.fhir.convertors (Maven): upgrade to 6.9.10 or later; ca.uhn.hapi.fhir:org.hl7.fhir.dstu2 (Maven): upgrade to 6.9.10 or later; ca.uhn.hapi.fhir:org.hl7.fhir.validation (Maven): upgrade to 6.9.10 or later; ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli (Maven): upgrade to 6.9.10 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-55470 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-55470?** Check whether you run ca.uhn.hapi.fhir:org.hl7.fhir.convertors (Maven), ca.uhn.hapi.fhir:org.hl7.fhir.dstu2 (Maven), ca.uhn.hapi.fhir:org.hl7.fhir.validation (Maven) or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- ca.uhn.hapi.fhir:org.hl7.fhir.convertors (Maven): upgrade to 6.9.10 or later

  ```sh
  # set ca.uhn.hapi.fhir:org.hl7.fhir.convertors to 6.9.10 in your pom.xml or build.gradle
  ```

- ca.uhn.hapi.fhir:org.hl7.fhir.dstu2 (Maven): upgrade to 6.9.10 or later

  ```sh
  # set ca.uhn.hapi.fhir:org.hl7.fhir.dstu2 to 6.9.10 in your pom.xml or build.gradle
  ```

- ca.uhn.hapi.fhir:org.hl7.fhir.validation (Maven): upgrade to 6.9.10 or later

  ```sh
  # set ca.uhn.hapi.fhir:org.hl7.fhir.validation to 6.9.10 in your pom.xml or build.gradle
  ```

- ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli (Maven): upgrade to 6.9.10 or later

  ```sh
  # set ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli to 6.9.10 in your pom.xml or build.gradle
  ```


## Technical details

The vulnerability is a Regular Expression Denial of Service (ReDoS) caused by an incomplete patch for CVE-2026-45367. While other modules were updated to use 'RegexTimeout' protection, the 'matches()' function in 'org.hl7.fhir.dstu2/utils/FHIRPathEngine.java' continued to call the raw 'String.matches()' method. An unauthenticated attacker can exploit this by submitting a FHIR resource or FHIRPath expression containing a complex regular expression designed to trigger catastrophic backtracking. This results in 100% CPU exhaustion on the host server. The issue is resolved in version 6.9.10 by ensuring all FHIRPath 'matches' calls are time-bounded.

## Affected products

- HAPI FHIR org.hl7.fhir.core < 6.9.10
- HAPI FHIR org.hl7.fhir.dstu2 <= 6.9.9
- HAPI FHIR org.hl7.fhir.validation <= 6.9.9

## Identifiers

- CVE-2026-55470
- GHSA-fxj4-p9xp-37v5

## Timeline

- 2026-06-12: patched: Version 6.9.10 released
- 2026-06-17: advisory: GitHub Security Advisory published
- 2026-07-08: disclosed: CVE-2026-55470 published to NVD

## References

- [https://github.com/hapifhir/org.hl7.fhir.core/commit/56376f7986222626af061ca7fc27ee1ab030e590](https://github.com/hapifhir/org.hl7.fhir.core/commit/56376f7986222626af061ca7fc27ee1ab030e590)
- [https://github.com/hapifhir/org.hl7.fhir.core/releases/tag/6.9.10](https://github.com/hapifhir/org.hl7.fhir.core/releases/tag/6.9.10)
- [https://github.com/hapifhir/org.hl7.fhir.core/security/advisories/GHSA-fxj4-p9xp-37v5](https://github.com/hapifhir/org.hl7.fhir.core/security/advisories/GHSA-fxj4-p9xp-37v5)

## Related threats

- [HAPI FHIR SHCParser DEFLATE infinite loop denial of service](https://junglewise.ai/threats/cve-2026-81876-hapi-fhir-shcparser-deflate-infinite-loop-denial-of-service)
- [HAPI FHIR SHCParser unbounded DEFLATE decompression denial of service](https://junglewise.ai/threats/cve-2026-81875-hapi-fhir-shcparser-unbounded-deflate-decompression-denial-of)
- [HAPI FHIR ReDoS in FHIRPathEngine](https://junglewise.ai/threats/cve-2026-49485-hapi-fhir-redos-in-fhirpathengine)
- [HAPI FHIR ReDoS in FHIRPathEngine](https://junglewise.ai/threats/cve-2026-45367-hapi-fhir-redos-in-fhirpathengine)
- [HAPI FHIR SSRF and credential leak in FHIR Validator](https://junglewise.ai/threats/cve-2026-34361-hapi-fhir-ssrf-and-credential-leak-in-fhir-validator)