hapifhir org.hl7.fhir.core up to 6.9.11 SHCParser SHCParser.java SHCParser.decodeJWT input validation

Summaryinfo

A vulnerability, which was classified as problematic, has been found in hapifhir org.hl7.fhir.core up to 6.9.11. The affected element is the function SHCParser.decodeJWT of the file org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/SHCParser.java of the component SHCParser. Performing a manipulation results in input validation. This vulnerability is identified as CVE-2026-81875. The attack can be initiated remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic has been found in hapifhir org.hl7.fhir.core up to 6.9.11. This affects the function SHCParser.decodeJWT of the file org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/SHCParser.java of the component SHCParser. The manipulation with an unknown input leads to a input validation vulnerability. CWE is classifying the issue as CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. This is going to have an impact on availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-81875 since 08/27/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 6.9.12 eliminates this vulnerability.

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Productinfo

Vendor

• hapifhir

Name

• org.hl7.fhir.core

Version

• 6.9.0
• 6.9.1
• 6.9.2
• 6.9.3
• 6.9.4
• 6.9.5
• 6.9.6
• 6.9.7
• 6.9.8
• 6.9.9
• 6.9.10
• 6.9.11

Website

• Product: https://github.com/hapifhir/org.hl7.fhir.core/

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