CVE-2026-45367Network attack vector

Service hang via unbounded FHIRPath regex evaluation

Published Jul 16, 2026 · Updated Jul 16, 2026

Regular expression denial of service in HAPI FHIR org.hl7.fhir.core before 6.9.7 allows remote attackers to hang validation services. FHIRPathEngine passes patterns from matches(), matchesFull(), and replaceMatches() directly to Java Pattern.compile() and String.replaceAll() without complexity limits or timeouts. An unauthenticated request that reaches FHIRPath evaluation can trigger catastrophic backtracking and exhaust a CPU core, interrupting the calling service.

CVSS severity7.5
High
EPSS probability0.68%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Regular expression denial of service in HAPI FHIR org.hl7.fhir.core before 6.9.7 allows remote attackers to hang validation services. FHIRPathEngine passes patterns from matches(), matchesFull(), and replaceMatches() directly to Java Pattern.compile() and String.replaceAll() without complexity limits or timeouts. An unauthenticated request that reaches FHIRPath evaluation can trigger catastrophic backtracking and exhaust a CPU core, interrupting the calling service.

The record

CVE
CVE-2026-45367
Published
Jul 16, 2026
Updated
Jul 16, 2026
Vendor
HAPI FHIR
Product
org.hl7.fhir.core
Classifications
CWE-1333, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 16, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 16, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 6.9.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

HAPI FHIR · org.hl7.fhir.coreversion=< 6.9.7

Published CVSS scores

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

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1333Inefficient Regular Expression Complexity
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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