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

Summaryinfo

A vulnerability described as problematic has been identified in HAPI FHIR 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. Such manipulation leads to input validation. This vulnerability is uniquely identified as CVE-2026-81876. The attack can be launched remotely. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in HAPI FHIR org.hl7.fhir.core up to 6.9.11. Affected by this issue 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. The manipulation with an unknown input leads to a input validation vulnerability. Using CWE to declare the problem leads to 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. Impacted is availability. CVE summarizes:

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 enter an infinite loop while processing attacker-controlled Smart Health Card JWT content whose header contains zip: "DEF" and whose raw-DEFLATE payload is empty or truncated. SHCParser.decodeJWT() reaches SHCParser.inflate(), where Inflater.inflate() can return zero while Inflater.finished() remains false and Inflater.needsInput() is true. The loop also lacks an Inflater.needsDictionary() termination check, SHCParser.decompress() contains the same zero-progress pattern, and ResourceChecker.java can reach SHC parsing during file-format detection. A malformed validation request can pin a JVM worker thread indefinitely, and concurrent requests can exhaust all validation workers. This issue is fixed in version 6.9.12.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-81876 since 08/27/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit.

Upgrading to version 6.9.12 eliminates this vulnerability.

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Productinfo

Vendor

• HAPI FHIR

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

CPE 2.3info

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CPE 2.2info

• 🔒
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• 🔒

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