OpenEMR Missing Authorization in Billing Module

Executive Summary

CVE-2026-124471 is a missing authorization vulnerability in OpenEMR versions before 8.3.0. It allows any authenticated user to bypass access controls and exploit an Insecure Direct Object Reference (IDOR) in the file interface/billing/sl_eob_invoice.php. Attackers can manipulate the 'id' parameter to read patient names, billing notes, and perform unauthorized actions like posting payments or deleting billing data for any patient.

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Detection Guidance

Check OpenEMR versions before 8.3.0 by running: grep -r 'openemr' /var/www/html/openemr/version.php or check the version in the OpenEMR web interface. Inspect network traffic for requests to interface/billing/sl_eob_invoice.php with manipulated 'id' parameters. Look for unauthorized POST requests modifying billing data or GET requests accessing patient billing notes.

Review server logs for repeated access to sl_eob_invoice.php with varying 'id' values, especially from low-privilege accounts. Use tools like Wireshark or tcpdump to monitor HTTP requests targeting the vulnerable endpoint.

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Impact Analysis

This vulnerability allows unauthorized users to access and modify sensitive billing data, including patient names, billing notes, and financial records. Attackers could forge payments, adjustments, or deletions, leading to financial fraud or disruptions in revenue cycles. Even low-privilege users like Front Office staff can exploit this to tamper with billing information.

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Compliance Impact

This vulnerability likely violates compliance with GDPR and HIPAA due to unauthorized access and modification of protected health information (PHI) and billing data. GDPR requires strict access controls and data protection, while HIPAA mandates safeguards for patient data integrity and confidentiality. Exploitation could lead to regulatory penalties and loss of trust.

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Mitigation Strategies

Upgrade OpenEMR to version 8.3.0 or later immediately. If upgrading is not possible, apply a patch to add access control checks in interface/billing/sl_eob_invoice.php. Restrict access to the billing module to authorized users only.

Monitor for suspicious activity in billing data and revoke any unauthorized changes. Implement network-level controls to block unauthorized access to the vulnerable endpoint until patched.

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