What is CVE-2026-40509?

CVE-2026-40509 is a medium-severity vulnerability in Openemr, classified under Cross-Site Request Forgery (CSRF). CVSS score: 4.3/10. Published 2026-08-19.

How severe is CVE-2026-40509?

Medium severity. CVSS v3 base score is 4.3 out of 10.

CSRF in Openemr

CVE-2026-40509

OpenEMR before 8.3.0 contains a cross-site request forgery vulnerability in the DICOM viewer. The web_path GET parameter in the DICOM viewer page is embedded unsanitized as a URL without validation against expected path formats. An attacker can craft a URL that causes an authenticated user with Patients - Documents permissions to make authenticated requests to arbitrary OpenEMR endpoints, enabling forced logout and other state-changing actions.

Vulnerability class: CSRF (Cross-Site Request Forgery)

Published 2026-08-19 · last modified 2026-09-09.

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.002 (7.8th percentile), scored 2026-10-05.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 8th percentile — 7.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.001 · newest: 0.002 · change: +0.001

Affected products

Openemr

Weakness classification (CWE)

CWE-352 — Cross-Site Request Forgery (CSRF)

References

Patch Commit (patch)
OpenEMR v8_3_0 Release Notes (release-notes)
GitHub Security Advisory (GHSA-wffp-pj5h-xqwp) (vendor-advisory)
www.vulncheck.com/advisories/openemr-csrf-via-dicom-viewer-web-path-parameter (third-party-advisory)

Frequently asked questions

What is CVE-2026-40509?: CVE-2026-40509 is a medium-severity vulnerability in Openemr, classified under Cross-Site Request Forgery (CSRF). CVSS score: 4.3/10. Published 2026-08-19.
How severe is CVE-2026-40509?: Medium severity. CVSS v3 base score is 4.3 out of 10.