# HAPI FHIR: SHCParser DEFLATE infinite loop causes denial of service Advisory record · `GHSA-gq9c-wmrm-5hvr` - **Identifiers:** `GHSA-gq9c-wmrm-5hvr` · `CVE-2026-81876` - **State:** Confirmed - **Severity:** CVSS 7.5 High - **Critical:** No - **Weakness (CWE):** [CWE-20](https://cwe.mitre.org/data/definitions/20.html) · [CWE-400](https://cwe.mitre.org/data/definitions/400.html) · [CWE-835](https://cwe.mitre.org/data/definitions/835.html) - **Tags:** [Denial of service](https://agentprime.io/advisories/tag/dos.md) · [CWE-20](https://agentprime.io/advisories/tag/cwe-20.md) - **Published:** 17 Sept 2026 - **Updated:** 17 Sept 2026 - **Reviewed by a person:** No Published by the GitHub Advisory Database at 17 Sept 2026, 20:32 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. ## Affected packages - `ca.uhn.hapi.fhir:org.hl7.fhir.r5` (Maven): affected `<6.9.12`; fixed in `6.9.12` - `ca.uhn.hapi.fhir:org.hl7.fhir.validation` (Maven): affected `<6.9.12`; fixed in `6.9.12` - `ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli` (Maven): affected `<6.9.12`; fixed in `6.9.12` ## Machine-written summary Summary written by Claude Haiku from the source advisory. Not reviewed by a person. > GHSA-gq9c-wmrm-5hvr affects the Maven packages ca.uhn.hapi.fhir:org.hl7.fhir.r5, ca.uhn.hapi.fhir:org.hl7.fhir.validation and ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli, versions before 6.9.12. A malformed Smart Health Card with a DEFLATE payload that is empty or truncated can cause the SHC parser to loop forever. An attacker who can submit SHC content for validation can tie up a worker thread indefinitely, causing denial of service. Upgrade to 6.9.12. Written 2 Nov 2026. ## Not analysed yet We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check. ## Severity and exploitation - 7.5 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`, from CNA (GitHub_M) - **CISA KEV:** Not listed. - **EPSS:** 0.0063, the 50th percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days. ## Timeline - 31 Oct 2026, 14:16 UTC: First seen by agentprime - 31 Oct 2026, 14:16 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-gq9c-wmrm-5hvr) ## Sources - [GitHub Advisory Database: GHSA-gq9c-wmrm-5hvr](https://github.com/advisories/GHSA-gq9c-wmrm-5hvr) - [OSV: GHSA-gq9c-wmrm-5hvr](https://osv.dev/vulnerability/GHSA-gq9c-wmrm-5hvr) - - - - - - Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code. ## Check whether this affects you A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet. - With the agentprime MCP server (), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: - In a browser: reads your lockfile in the browser, never uploading it. - Whether it touches your code, with file and line: the Claude Code plugin, - As JSON: , or `POST https://api.agentprime.io/v1/match` with your packages () --- The web page: . Everything for agents: .