CVE-2026-124471 in OpenEMR
Summary
by MITRE • 11/08/2026
OpenEMR before 8.3.0 contains a missing authorization vulnerability in interface/billing/sl_eob_invoice.php that allows any authenticated user to read and modify billing data for any encounter. Attackers can iterate the id parameter to read patient names and billing notes, and post payments, adjustments, deletions, or billing notes against any patient's account.
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Analysis
by VulDB Data Team • 11/08/2026
The vulnerability identified in OpenEMR versions prior to 8.3.0 represents a critical failure in access control mechanisms within the application's billing module. Specifically located at interface/billing/sl_eob_invoice.php, this flaw allows authenticated users to bypass intended authorization checks when interacting with electronic obstetrics and gynecology invoice data. In secure software architecture, every request that modifies or retrieves sensitive state must be validated against the user's permissions relative to the specific resource being accessed. Here, the system fails to verify whether the requesting user has legitimate ownership or administrative rights over the encounter ID provided in the request parameters. This absence of server-side authorization logic creates a direct path for unauthorized data manipulation and disclosure, undermining the fundamental security principle that users should only access resources associated with their own authorized scope.
From a technical perspective, the exploitation vector relies on the predictable nature of integer-based identifiers often used to reference database records such as patient encounters or billing invoices. An attacker who has successfully authenticated into the OpenEMR system can manipulate the id parameter in HTTP requests directed at sl_eob_invoice.php. By iterating through sequential values for this identifier, an adversary can systematically probe the backend database structure. Because there is no check ensuring that the encounter ID belongs to a patient assigned to or visible by the current user session, the application processes these requests as valid operations regardless of their legitimacy. This behavior effectively turns standard CRUD (Create, Read, Update, Delete) functionalities into tools for mass data exfiltration and malicious modification.
The operational impact of this vulnerability is severe due to the sensitive nature of healthcare billing information. The ability to read patient names and associated billing notes constitutes a significant breach of confidentiality, potentially violating regulations such as HIPAA in the United States or GDPR in Europe if personal health information is exposed without consent. Furthermore, the capability to post payments, apply adjustments, delete existing records, or inject false billing notes introduces profound integrity risks. Malicious actors could manipulate financial records to cover up fraud, create phantom charges for reimbursement schemes, or erase evidence of previous transactions. For healthcare providers, this not only compromises patient trust but also exposes them to legal liability and regulatory penalties stemming from the mishandling of protected health information and inaccurate financial reporting.
This vulnerability aligns with CWE-284, which describes Improper Access Control, specifically highlighting failures in verifying user privileges for specific actions on resources. It is further categorized under CWE-639, Authorization Bypass Through User-Controlled Key, as the attacker leverages a controllable identifier to access unauthorized data. In terms of offensive security frameworks, this behavior maps directly to MITRE ATT&CK technique T1078, Valid Accounts, where an adversary uses legitimate credentials to move laterally or escalate privileges within a system. Additionally, the ability to modify billing records corresponds to T1496, Resource Hijacking, if used for financial gain, or more broadly to data manipulation tactics that disrupt organizational operations and integrity.
Mitigation strategies must prioritize immediate patching of the OpenEMR installation to version 8.3.0 or later, where these authorization checks have been rectified by the developers. Until an upgrade is feasible, administrators should implement strict input validation on the server side for all billing-related endpoints, ensuring that every request includes a verification step against user-specific encounter lists stored in session variables or database queries with explicit ownership filters. Network-level controls such as Web Application Firewalls can also be configured to detect and block anomalous patterns of sequential ID enumeration attempts targeting billing modules. Regular security audits focusing on access control logic across all administrative interfaces are essential to prevent similar authorization bypasses from occurring elsewhere in the application ecosystem.