XSS in Openemr
CVE-2026-40507
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.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.003 (24.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 25th percentile — 24.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
Affected products
Weakness classification (CWE)
References
- GitHub Security Advisory (GHSA-rmmr-8498-463g) (vendor-advisory)
- OpenEMR v8_3_0 Release Notes (release-notes)
- Patch Commit (patch)
- www.vulncheck.com/advisories/openemr-reflected-xss-via-templatehtml-parameter-i… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-40507?
- CVE-2026-40507 is a medium-severity vulnerability in Openemr, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-08-19.
- How severe is CVE-2026-40507?
- Medium severity. CVSS v3 base score is 6.1 out of 10.