CVE-2021-25919 is a stored Cross-Site Scripting (XSS) vulnerability affecting OpenEMR versions 5.0.2 through 6.0.0. OpenEMR is an open-source electronic medical record and practice management software widely used in healthcare settings. The vulnerability arises because user input fields, specifically those used when creating a new user, do not properly validate or sanitize input. This allows a highly privileged attacker—someone with the ability to create new users—to inject arbitrary malicious scripts into the application. When these scripts are stored and later rendered in the application interface, they can execute in the context of other users’ browsers. The CVSS 3.1 base score is 4.8, indicating a medium severity level. The vector string (AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N) shows that the attack can be performed remotely over the network with low attack complexity but requires high privileges and user interaction (the victim must trigger the malicious script). The scope is changed, meaning the vulnerability affects components beyond the initially vulnerable component. The impact affects confidentiality and integrity to a limited extent but does not affect availability. No known exploits have been reported in the wild. The vulnerability is classified under CWE-79, which corresponds to improper neutralization of input leading to XSS. Since OpenEMR is used to manage sensitive patient data, exploitation could lead to theft of session tokens, unauthorized actions on behalf of users, or disclosure of sensitive information through script execution in victim browsers. However, exploitation requires an attacker to have high privileges to create users, limiting the attack surface to insider threats or compromised privileged accounts.

For European organizations, particularly healthcare providers using OpenEMR, this vulnerability poses a risk of unauthorized access to sensitive patient data and potential manipulation of user sessions. Although exploitation requires high privileges, if an attacker gains such access—through phishing, credential theft, or insider compromise—they could inject malicious scripts that execute when other privileged users access the system. This could lead to theft of authentication tokens, enabling lateral movement or privilege escalation, and potentially exposing patient health information, violating GDPR regulations. The integrity of user data and system operations could be compromised, undermining trust in healthcare IT systems. Given the critical nature of healthcare data and the regulatory environment in Europe, even a medium-severity vulnerability like this can have significant compliance and reputational consequences. The lack of known exploits reduces immediate risk but does not eliminate the threat, especially in targeted attacks against healthcare institutions.

1. Immediate patching or upgrading OpenEMR to a version beyond 6.0.0 where this vulnerability is fixed, if available. Since no patch links are provided, organizations should monitor official OpenEMR channels for updates or apply community-provided patches. 2. Implement strict input validation and output encoding on all user input fields, especially those related to user creation and management, to prevent injection of malicious scripts. 3. Restrict the ability to create new users to a minimal number of trusted administrators and enforce strong authentication mechanisms (e.g., multi-factor authentication) to reduce risk of privileged account compromise. 4. Conduct regular audits of user accounts and monitor logs for suspicious user creation activities or anomalous behavior indicative of exploitation attempts. 5. Employ Content Security Policy (CSP) headers to limit the execution of unauthorized scripts in the application context, mitigating impact if XSS payloads are injected. 6. Educate privileged users about the risks of phishing and social engineering attacks that could lead to credential compromise. 7. Consider deploying Web Application Firewalls (WAF) with custom rules to detect and block common XSS payloads targeting OpenEMR interfaces. 8. Isolate OpenEMR instances within secure network segments and limit access to trusted networks and devices to reduce exposure.