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High · 7.5 CVE-2026-81875 EUVD-2026-80993GHSA-3w98-rrpr-fprr

HAPI FHIR: SHCParser unbounded DEFLATE decompression causes denial of service

Published Sep 16, 2026 · Updated Sep 17, 2026 · Assigned by GitHub_M

Description

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.

Affected products

VendorProductAffectedFixed
hapifhir org.hl7.fhir.core < 6.9.12 —

Affected packages

References