HAPI FHIR: ReDoS via FHIRPath matches()/replaceMatches() in FHIR Validator HTTP Endpoint

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-45367: 0.68% estimated exploitation activity in the next 30 days; percentile 52.62 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary All implementations of FHIRPathEngine accept arbitrary FHIRPath expressions and evaluate them without input validation. The FHIRPath functions matches(), matchesFull(), and replaceMatches() pass user-controlled regular expressions directly to Java's Pattern.compile() and String.replaceAll() without complexity checks or timeouts. An attacker can send a resource containing an evil regex pattern that causes catastrophic backtracking, exhausting system resources, and causing Denial-of-Service. Details The vulnerability exists in regex execution in FHIRPathEngine implementations across multiple code modules. For example the org.hl7.fhir.r5 module: Entry point 1 — FHIRPathEngine.java:5929 (R5 funcMatches): Entry point 2 — FHIRPathEngine.java:5951 (R5 funcMatchesFull): Entry point 3 — FHIRPathEngine.java:5120 (R5 funcReplaceMatches): The same vulnerabilities exist in the dstu2, dstu2016may, dstu3, r4, and r4b modules, and the FHIRPathEngine is used in the validation module…

Published by the source

18 May 2026, 20:23 UTC

Last modified by the source

18 May 2026, 20:23 UTC

Source last checked

26 Oct 2026, 16:45 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-3653-68v6-rq57

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# Patch Next advisory brief: CVE-2026-45367

Advisory: HAPI FHIR: ReDoS via FHIRPath matches()/replaceMatches() in FHIR Validator HTTP Endpoint
IDs: CVE-2026-45367, GHSA-3653-68v6-rq57
Record: https://patchnext.com/advisories/cve-2026-45367 (revision 1, source checked 26 Oct 2026, 16:45 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli 6.9.7; ca.uhn.hapi.fhir:org.hl7.fhir.dstu2016may 6.9.7; ca.uhn.hapi.fhir:org.hl7.fhir.dstu3 6.9.7; ca.uhn.hapi.fhir:org.hl7.fhir.validation 6.9.7; ca.uhn.hapi.fhir:org.hl7.fhir.r4b 6.9.7; ca.uhn.hapi.fhir:org.hl7.fhir.r4 6.9.7; ca.uhn.hapi.fhir:org.hl7.fhir.dstu2 6.9.7; ca.uhn.hapi.fhir:org.hl7.fhir.r5 6.9.7. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli: affected <= 6.9.6; fixed in 6.9.7
- Maven ca.uhn.hapi.fhir:org.hl7.fhir.dstu2016may: affected <= 6.9.6; fixed in 6.9.7
- Maven ca.uhn.hapi.fhir:org.hl7.fhir.dstu3: affected <= 6.9.6; fixed in 6.9.7
- Maven ca.uhn.hapi.fhir:org.hl7.fhir.validation: affected <= 6.9.6; fixed in 6.9.7
- Maven ca.uhn.hapi.fhir:org.hl7.fhir.r4b: affected <= 6.9.6; fixed in 6.9.7
- Maven ca.uhn.hapi.fhir:org.hl7.fhir.r4: affected <= 6.9.6; fixed in 6.9.7
- Maven ca.uhn.hapi.fhir:org.hl7.fhir.dstu2: affected <= 6.9.6; fixed in 6.9.7
- Maven ca.uhn.hapi.fhir:org.hl7.fhir.r5: affected <= 6.9.6; fixed in 6.9.7

## Suggested inspection (read-only)
- Maven ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli: check the installed version with your package manager.
- Maven ca.uhn.hapi.fhir:org.hl7.fhir.dstu2016may: check the installed version with your package manager.
- Maven ca.uhn.hapi.fhir:org.hl7.fhir.dstu3: check the installed version with your package manager.
- Maven ca.uhn.hapi.fhir:org.hl7.fhir.validation: check the installed version with your package manager.
- Maven ca.uhn.hapi.fhir:org.hl7.fhir.r4b: check the installed version with your package manager.
- Maven ca.uhn.hapi.fhir:org.hl7.fhir.r4: check the installed version with your package manager.
- Maven ca.uhn.hapi.fhir:org.hl7.fhir.dstu2: check the installed version with your package manager.
- Maven ca.uhn.hapi.fhir:org.hl7.fhir.r5: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli, ca.uhn.hapi.fhir:org.hl7.fhir.dstu2016may, ca.uhn.hapi.fhir:org.hl7.fhir.dstu3, ca.uhn.hapi.fhir:org.hl7.fhir.validation, ca.uhn.hapi.fhir:org.hl7.fhir.r4b, ca.uhn.hapi.fhir:org.hl7.fhir.r4, ca.uhn.hapi.fhir:org.hl7.fhir.dstu2, ca.uhn.hapi.fhir:org.hl7.fhir.r5.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-3653-68v6-rq57 (GitHub-reviewed advisory GHSA-3653-68v6-rq57 lists affected ranges: Maven ca.uhn.hapi.fhir:org.hl7.fhir.dstu2 >=0 =0 =0 =0 =0 =0 =0 <=6.9.6; Maven…)

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