CVE-2020-5728 in OpenMRS
Summary
by MITRE
OpenMRS 2.9 and prior copies "Referrer" header values into an html element named "redirectUrl" within many webpages (such as login.htm). There is insufficient validation for this parameter, which allows for the possibility of cross-site scripting.
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Analysis
by VulDB Data Team • 05/06/2025
The vulnerability identified as CVE-2020-5728 affects OpenMRS versions 2.9 and earlier, representing a critical cross-site scripting vulnerability that stems from improper input validation within the application's web interface. This flaw exists in the handling of HTTP header values, specifically the "Referrer" header, which is being directly copied into an HTML element named "redirectUrl" without adequate sanitization or validation measures. The vulnerability manifests across multiple webpages including the login.htm page, making it particularly dangerous as it can be exploited during authentication processes when users are most vulnerable to attack vectors.
The technical implementation of this vulnerability involves the application's failure to properly validate or sanitize the Referrer header value before incorporating it into the redirectUrl HTML element. This creates a classic XSS attack surface where malicious actors can inject arbitrary JavaScript code through the referrer header, which then executes in the context of the victim's browser when the webpage loads. The vulnerability falls under CWE-79 - Improper Neutralization of Input During Web Page Generation, which specifically addresses the failure to properly sanitize user input that gets rendered in web content. The flaw represents a failure in the principle of least privilege and input validation, as the application assumes all referrer values are safe without proper sanitization mechanisms.
From an operational perspective, this vulnerability poses significant risks to healthcare organizations using OpenMRS systems, as it can be exploited to steal session cookies, perform unauthorized actions on behalf of authenticated users, or redirect users to malicious sites. The attack vector is particularly insidious because it leverages the Referrer header, which is automatically sent by browsers during navigation and is often trusted by web applications. Attackers can craft malicious referrer values that contain JavaScript payloads, potentially leading to session hijacking, data exfiltration, or further exploitation of the healthcare system. The impact is amplified in healthcare environments where patient data confidentiality and system integrity are paramount, as this vulnerability could compromise sensitive medical information and violate regulatory compliance requirements.
The mitigation strategies for this vulnerability should focus on implementing proper input validation and sanitization mechanisms for all user-supplied data, particularly HTTP headers that are processed by the application. Organizations should immediately upgrade to OpenMRS versions that have addressed this vulnerability, as the fix typically involves implementing proper HTML escaping or sanitization of the redirectUrl parameter before rendering it in the web interface. Additionally, implementing Content Security Policy headers can provide an additional layer of protection against XSS attacks, and regular security testing including dynamic application security testing should be conducted to identify similar vulnerabilities. This vulnerability aligns with ATT&CK technique T1059.007 - Command and Scripting Interpreter: JavaScript, as it enables attackers to execute malicious JavaScript code through the XSS vector. The remediation process should also include comprehensive security training for developers on secure coding practices and input validation to prevent similar issues in future application development cycles.