CPU exhaustion via unbounded FHIRPath regex evaluation
Published Jul 17, 2026 · Updated Jul 17, 2026
ReDoS in org.hl7.fhir.core before 6.9.4.2 and 6.9.5 through 6.9.8 allows remote attackers to hang FHIRPath callers. The matches(), matchesFull(), and replaceMatches() functions pass attacker-controlled patterns into Java regex operations through a timeout utility whose worker continues after cancellation, while three modules bypass the utility. Reachability requires an application to evaluate attacker-supplied FHIR resources or FHIRPath expressions; catastrophic backtracking can pin a CPU core and interrupt the service.
Summary
What happened
ReDoS in org.hl7.fhir.core before 6.9.4.2 and 6.9.5 through 6.9.8 allows remote attackers to hang FHIRPath callers. The matches(), matchesFull(), and replaceMatches() functions pass attacker-controlled patterns into Java regex operations through a timeout utility whose worker continues after cancellation, while three modules bypass the utility. Reachability requires an application to evaluate attacker-supplied FHIR resources or FHIRPath expressions; catastrophic backtracking can pin a CPU core and interrupt the service.
The record
- CVE
- CVE-2026-49485
- Published
- Jul 17, 2026
- Updated
- Jul 17, 2026
- Vendor
- HAPI FHIR
- Product
- org.hl7.fhir.core
- Classifications
- CWE-1333, CWE-400, T1499.003
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 17, 2026CVE publishedPublication date reported by the CVE source.
- Jul 17, 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.
- Affected versionversion=< 6.9.4.2
- Affected versionversion=>= 6.9.5, < 6.9.9
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
- GHSA catastrophic-backtracking regex exampleproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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