TI-2026-56487 Aliases CVE-2026-81875 GHSA-3w98-rrpr-fprr

HAPI FHIR: SHCParser unbounded DEFLATE decompression causes denial of service

HIGH 72CWE-20Published 2026-09-16 · Updated 2026-09-17

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-400.

Summary

HAPI FHIR is a complete implementation of the HL7 FHIR standard for healthcare interoperability in Java. Prior to version 6.9.12, SHCParser in org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/SHCParser.java can consume attacker-controlled Smart Health Card JWT content whose header contains zip: "DEF" and whose small raw-DEFLATE payload expands to a very large value. SHCParser.decodeJWT() passes the decoded payload to SHCParser.inflate(), which accumulates all decompressed bytes in a ByteArrayOutputStream without an output-size limit before JSON parsing, and SHCParser.decompress() contains the same unbounded pattern. An application or validator service that accepts attacker-supplied SHC content can therefore suffer excessive heap allocation, severe garbage-collection pressure, request failure, process instability, or process termination. This issue is fixed in version 6.9.12.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.0063 50th percentileScored 2026-11-07

Fix Fixed org.hl7.fhir.core (hapifhir): 6.9.12ca.uhn.hapi.fhir:org.hl7.fhir.r5 (Maven): 6.9.12+1 more product

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
hapifhir	org.hl7.fhir.core	before 6.9.12	6.9.12	Patch available	CNA
—	ca.uhn.hapi.fhir:org.hl7.fhir.r5 (Maven)	before 6.9.12	6.9.12	Patch available	GHSA-3w98-rrpr-fprr
—	ca.uhn.hapi.fhir:org.hl7.fhir.validation (Maven)	before 6.9.12	6.9.12	Patch available	GHSA-3w98-rrpr-fprr
—	ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli (Maven)	up to 5.0.0	—	No fix listed	GHSA-3w98-rrpr-fprr

org.hl7.fhir.core Vendorhapifhir Affected before 6.9.12 Fixed in 6.9.12 Patch available CNA
ca.uhn.hapi.fhir:org.hl7.fhir.r5 (Maven) Vendor— Affected before 6.9.12 Fixed in 6.9.12 Patch available GHSA-3w98-rrpr-fprr
ca.uhn.hapi.fhir:org.hl7.fhir.validation (Maven) Vendor— Affected before 6.9.12 Fixed in 6.9.12 Patch available GHSA-3w98-rrpr-fprr
ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli (Maven) Vendor— Affected up to 5.0.0 Fixed in — No fix listed GHSA-3w98-rrpr-fprr

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:a:hapifhir:hl7_fhir_core::::::::	—	—	hapifhir

cpe:2.3:a:hapifhir:hl7_fhir_core:*:*:*:*:*:*:*:* Versions — — ·hapifhir

Remediation

Fix · CNA org.hl7.fhir.core (hapifhir) Fixed in 6.9.12
Fix · GHSA-3w98-rrpr-fprr ca.uhn.hapi.fhir:org.hl7.fhir.r5 (Maven) Fixed in 6.9.12 Advisory →
Fix · GHSA-3w98-rrpr-fprr ca.uhn.hapi.fhir:org.hl7.fhir.validation (Maven) Fixed in 6.9.12 Advisory →

Timeline

2026-10-02 Threatist record created from CVE-2026-81875
2026-10-03 Alias added: GHSA-3w98-rrpr-fprr
2026-10-28 EPSS moved to the 50th–90th percentile

References

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2026-81875

Other 6

TI-2026-26647 HAPI FHIR: Unauthenticated SSRF via /loadIG Chains with startsWith() Credential Leak for Authentication Token Theft CVSS 3.1CRITICAL 9.3
TI-2026-40028 HAPI FHIR: XXE in XsltUtilities.saxonTransform via unhardened Saxon TransformerFactory CVSS 4.0HIGH 8.7
TI-2026-26645 HAPI FHIR: Authentication Credential Leakage via Improper URL Prefix Matching on HTTP Redirect in HAPI FHIR Core CVSS 3.1CRITICAL 9.1
TI-2026-56488 HAPI FHIR: SHCParser DEFLATE infinite loop causes denial of service CVSS 3.1HIGH 7.5
TI-2026-44485 HAPI FHIR: XHTML narrative parser unbounded recursion causes StackOverflow denial of service CVSS 3.1HIGH 7.5
TI-2026-44484 HAPI FHIR: JSON utility parser unbounded recursion causes StackOverflow denial of service CVSS 3.1HIGH 7.5

See all 17 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences