OpenEMR < 8.3.0 Reflected XSS via templateHtml Parameter in Patient Portal (CVE-2026-40507) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-40507

OpenEMR < 8.3.0 Reflected XSS via templateHtml Parameter in Patient Portal

Answer in brief

CVE-2026-40507 records a Unknown severity vulnerability in OpenEMR < 8.3.0 Reflected XSS via templateHtml Parameter in Patient Portal. The current sources do not mark it as known exploited. The current feed maps openemr/openemr (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 19, 2026Updated Aug 19, 2026Source checked Aug 19, 2026First seen by HOL Aug 19, 2026Material review Aug 19, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps openemr/openemr (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
openemr/openemrgeneric	>=0 <8.3.0	8.3.0

Recommended response

Check inventory. Check lockfiles and deployed manifests for openemr/openemr.
Review the reported fix. Update openemr/openemr to 8.3.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 19, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 19, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 19, 2026

Sources and claim methodology

Upstream source description

OpenEMR before 8.3.0 contains a reflected cross-site scripting vulnerability in the patient portal template import handler. The templateHtml GET parameter is reflected into the page response without sanitization. An attacker can craft a URL that executes arbitrary JavaScript in the browser of any authenticated user with Forms Administration permissions who visits the link, enabling session hijacking.

Quoted source text, attributed separately from HOL analysis.