CVE-2026-24847: OpenEMR CSRF Vulnerability

CVE-2026-24847 Overview

CVE-2026-24847 is an Open Redirect vulnerability affecting OpenEMR, a free and open source electronic health records and medical practice management application. Prior to version 8.0.0, the Eye Exam form module allows any authenticated user to be redirected to an arbitrary external URL. This vulnerability can be exploited to conduct phishing attacks against healthcare providers using OpenEMR, potentially leading to credential theft and compromise of sensitive patient data.

Critical Impact

Healthcare providers using vulnerable OpenEMR installations are at risk of phishing attacks that could lead to credential theft, unauthorized access to patient records, and potential HIPAA compliance violations.

Affected Products

• OpenEMR versions prior to 8.0.0
• Open-emr OpenEMR (cpe:2.3:a:open-emr:openemr:*:*:*:*:*:*:*:*)

Discovery Timeline

• February 25, 2026 - CVE-2026-24847 published to NVD
• February 26, 2026 - Last updated in NVD database

Technical Details for CVE-2026-24847

Vulnerability Analysis

This vulnerability is classified as CWE-601 (URL Redirection to Untrusted Site), commonly known as an Open Redirect. The vulnerability exists in the Eye Exam form module of OpenEMR, specifically in the interface/forms/eye_mag/view.php file. The vulnerable code accepts a url parameter from user input and directly uses it in an HTTP Location header without proper validation, allowing attackers to redirect authenticated users to malicious external websites.

The attack requires user interaction—an authenticated user must click a crafted link. However, once clicked, the victim is seamlessly redirected to an attacker-controlled site that may impersonate the legitimate OpenEMR login page. In healthcare environments, this poses significant risks as attackers could harvest credentials to access protected health information (PHI).

Root Cause

The root cause of this vulnerability is improper validation of the url parameter in interface/forms/eye_mag/view.php. The application directly used the user-supplied URL value in an HTTP redirect without validating that the destination URL belongs to a trusted domain or is a relative path within the application.

Attack Vector

An attacker can exploit this vulnerability by crafting a malicious URL that includes an external redirect destination. When an authenticated OpenEMR user clicks the crafted link, they are redirected to the attacker-controlled website. This is particularly dangerous in healthcare settings where phishing pages could mimic legitimate login screens to harvest credentials.

Example attack scenario:

1. Attacker crafts a URL containing the malicious redirect parameter
2. Attacker sends the link to a healthcare provider via email or other communication
3. The victim, seeing a legitimate OpenEMR domain, clicks the link
4. The victim is redirected to a phishing page that mimics OpenEMR's login
5. Credentials entered on the phishing page are captured by the attacker

// Vulnerable code removed in patch (interface/forms/eye_mag/view.php)
// The following lines were removed to fix CVE-2026-24847:

-if (!empty($_REQUEST['url'])) {
-    header('Location: ' . $_REQUEST['url']);
-    exit;
-}

// The fix completely removes the open redirect functionality
// Source: https://github.com/openemr/openemr/commit/b924459bb5b2844f8f5d3d6cedd2e854eda20aad

Detection Methods for CVE-2026-24847

Indicators of Compromise

• Web server logs showing requests to /interface/forms/eye_mag/view.php with suspicious url parameters containing external domains
• HTTP 302 redirects from OpenEMR to external, untrusted websites
• User reports of unexpected redirects when using the Eye Exam form module
• Authentication attempts from unusual locations following use of OpenEMR

Detection Strategies

• Monitor web application firewall (WAF) logs for requests containing url parameters with external domain references in the Eye Exam form endpoints
• Implement detection rules for HTTP redirect responses (302/301) from OpenEMR to non-whitelisted external domains
• Review application logs for patterns of access to /interface/forms/eye_mag/view.php with URL parameters
• Deploy phishing detection systems to identify credential harvesting pages impersonating OpenEMR

Monitoring Recommendations

• Enable verbose logging on web servers hosting OpenEMR to capture full request parameters
• Implement real-time alerting for redirect responses to external domains from OpenEMR endpoints
• Monitor for spikes in failed authentication attempts that may indicate successful phishing campaigns
• Track user session anomalies that could indicate compromised credentials

How to Mitigate CVE-2026-24847

Immediate Actions Required

• Upgrade OpenEMR to version 8.0.0 or later immediately
• Review web server logs for evidence of exploitation attempts
• Educate healthcare staff about phishing risks and suspicious links
• Implement web application firewall rules to block requests with external URLs in the url parameter

Patch Information

OpenEMR has released version 8.0.0 which addresses this vulnerability. The fix removes the vulnerable redirect functionality entirely from the Eye Exam form module. The security patch is available in commit b924459bb5b2844f8f5d3d6cedd2e854eda20aad.

For detailed patch information, see the GitHub Security Advisory GHSA-6f42-6q2r-fc2h and the GitHub Commit Details.

Workarounds

• If immediate upgrade is not possible, implement WAF rules to block requests to /interface/forms/eye_mag/view.php containing external URLs in the url parameter
• Restrict access to the Eye Exam form module to only necessary users
• Implement Content Security Policy (CSP) headers to limit redirect destinations

# Apache mod_rewrite rule to block malicious redirects (temporary workaround)
# Add to .htaccess or Apache configuration

RewriteEngine On
RewriteCond %{QUERY_STRING} url=https?:// [NC]
RewriteCond %{REQUEST_URI} /interface/forms/eye_mag/view\.php [NC]
RewriteRule ^ - [F,L]