CVE-2026-25220: OpenEMR Auth Bypass Vulnerability

CVE-2026-25220 Overview

CVE-2026-25220 is an authorization bypass vulnerability in OpenEMR, a free and open source electronic health records (EHR) and medical practice management application. The vulnerability exists in the Message Center component, where the show_all=yes URL parameter is passed to the getPnotesByUser() function without proper authorization verification. This allows any authenticated user to access all internal messages across the entire system, regardless of their administrative privileges.

Critical Impact

Any authenticated OpenEMR user can view the complete internal message list containing sensitive patient and staff communications by simply requesting messages.php?show_all=yes, bypassing intended access controls.

Affected Products

• OpenEMR versions prior to 8.0.0
• OpenEMR Message Center component (messages.php)
• Healthcare organizations using vulnerable OpenEMR installations

Discovery Timeline

• 2026-02-25 - CVE CVE-2026-25220 published to NVD
• 2026-02-26 - Last updated in NVD database

Technical Details for CVE-2026-25220

Vulnerability Analysis

This vulnerability is classified under CWE-639: Authorization Bypass Through User-Controlled Key. The core issue lies in the Message Center's handling of the show_all parameter, which controls whether a user can view all internal messages or only their own. The backend implementation fails to verify that the requesting user possesses administrator privileges before honoring the show_all=yes request.

The attack requires network access and low-privilege authentication (any valid OpenEMR user account). Once authenticated, an attacker can access confidential internal communications that may contain sensitive patient health information (PHI), staff discussions, and other protected data. In healthcare environments governed by regulations like HIPAA, this represents a significant compliance risk.

Root Cause

The root cause is a missing authorization check in the messages.php endpoint. When processing the show_all URL parameter, the application directly passes the user-supplied value to the getPnotesByUser() function without first validating that the user has administrative privileges. Additionally, the "Show All" link is incorrectly visible to non-admin users in the interface, creating both a backend authorization gap and a UI-level information disclosure.

Attack Vector

The attack vector is network-based and requires only basic authentication. An attacker with any valid user account can exploit this vulnerability by:

1. Authenticating to the OpenEMR application with any user credentials
2. Navigating to or directly requesting messages.php?show_all=yes
3. Receiving the complete list of internal messages from all users

The exploitation is trivial and requires no special tools or technical expertise beyond basic web browser usage.

                             $messages = xl('My Messages');
                         }
                     } else {
+                        $show_all = "no";
                         $messages = xlt('My Messages');
                     }
                     ?>

Source: GitHub Commit Details

The patch forces $show_all to "no" for non-administrative users, ensuring that the parameter cannot be manipulated to bypass authorization controls.

Detection Methods for CVE-2026-25220

Indicators of Compromise

• HTTP requests to messages.php containing the show_all=yes parameter from non-administrator accounts
• Unusual access patterns to the Message Center from users who typically don't access administrative functions
• Log entries showing multiple users accessing the full message list unexpectedly
• Audit trail anomalies indicating unauthorized access to internal communications

Detection Strategies

• Monitor web server access logs for requests matching the pattern messages.php?show_all=yes
• Implement application-layer monitoring to detect parameter manipulation attempts
• Configure SentinelOne Singularity to monitor for suspicious web application behavior patterns
• Review OpenEMR audit logs for unauthorized message access events

Monitoring Recommendations

• Enable detailed logging for the OpenEMR Message Center component
• Implement real-time alerting for show_all parameter usage by non-admin users
• Deploy web application firewall (WAF) rules to detect and block exploitation attempts
• Conduct periodic access reviews of internal message viewing patterns

How to Mitigate CVE-2026-25220

Immediate Actions Required

• Upgrade OpenEMR to version 8.0.0 or later immediately
• Review access logs to determine if this vulnerability has been exploited
• Audit all user accounts and verify appropriate privilege levels
• Notify affected parties if unauthorized access to sensitive messages is confirmed

Patch Information

OpenEMR version 8.0.0 addresses this vulnerability by implementing proper authorization checks. The security patch is available via the GitHub Commit. The fix ensures that non-administrative users cannot use the show_all parameter to bypass access controls. For detailed information, refer to the GitHub Security Advisory GHSA-phcp-7qjx-83cm.

Workarounds

• Implement a web application firewall rule to block requests containing show_all=yes from non-admin users
• Restrict access to messages.php at the network level to trusted administrative IP addresses
• Consider disabling the Message Center feature temporarily until patching is complete
• Manually apply the patch logic by modifying interface/main/messages/messages.php to force $show_all = "no" for non-admin users

# Example Apache mod_rewrite rule to block exploitation attempts
# Add to OpenEMR .htaccess or Apache configuration
RewriteEngine On
RewriteCond %{QUERY_STRING} show_all=yes [NC]
RewriteCond %{REQUEST_URI} messages\.php [NC]
RewriteRule ^(.*)$ - [F,L]