CVE-2026-81875

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.

• https://github.com/hapifhir/org.hl7.fhir.core/commit/fbb94216e0ad21ded75be77e5e20242ba194e83f
• https://github.com/hapifhir/org.hl7.fhir.core/pull/2493
• https://github.com/hapifhir/org.hl7.fhir.core/releases/tag/6.9.11
• https://github.com/hapifhir/org.hl7.fhir.core/releases/tag/6.9.12
• https://github.com/hapifhir/org.hl7.fhir.core/security/advisories/GHSA-3w98-rrpr-fprr
• https://github.com/hapifhir/org.hl7.fhir.core/security/advisories/GHSA-3w98-rrpr-fprr