Infinite loop in FHIR - CVE-2026-81876
Published: September 1, 2026
Vulnerability identifier: #VU146602
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-81876
CWE-ID: CWE-835
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to loop with an unreachable exit condition in SHCParser.inflate() and SHCParser.decompress() when processing SHC content containing an empty or truncated DEFLATE payload with zip: \"DEF\". A remote attacker can submit specially crafted SHC content for validation to cause a denial of service.
The issue is reachable during SHC validation and during file-format detection for SHC-looking input, and a single malformed validation request can pin a JVM worker thread indefinitely.
Affected software
FHIR
How to mitigate CVE-2026-81876
Install security update from vendor's website.
FHIR - update to 6.9.12