CVE-2023-4978 in librenms
Summary
by MITRE • 09/15/2023
Cross-site Scripting (XSS) - DOM in GitHub repository librenms/librenms prior to 23.9.0.
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Analysis
by VulDB Data Team • 05/08/2026
Cross-site scripting vulnerabilities in the DOM context represent a critical class of web application security flaws that allow attackers to inject malicious scripts into web pages viewed by other users. The specific vulnerability identified in the librenms/librenms repository affects versions prior to 23.9.0 and demonstrates how client-side script execution can be manipulated through DOM-based input handling. This type of vulnerability falls under CWE-79 which specifically addresses cross-site scripting flaws in web applications. The DOM-based XSS vulnerability occurs when web applications use untrusted data in the construction of dynamic JavaScript code without proper sanitization or encoding, creating opportunities for malicious script injection.
The technical flaw in this librenms implementation stems from improper handling of user-supplied input within the Document Object Model of web pages. When the application processes user data through DOM methods such as innerHTML, document.write, or similar functions, it fails to adequately sanitize or escape the input before incorporating it into the page's dynamic content. This allows attackers to inject malicious JavaScript code that executes in the context of other users' browsers. The vulnerability is particularly concerning because it operates entirely on the client-side without requiring server-side modifications, making it more difficult to detect and prevent through traditional server-side security measures.
The operational impact of this DOM-based XSS vulnerability in the librenms monitoring platform could be severe for organizations relying on the system for network infrastructure management. Attackers could exploit this vulnerability to steal session cookies, perform unauthorized actions on behalf of legitimate users, redirect victims to malicious websites, or even exfiltrate sensitive network monitoring data. Given that librenms is designed for network operations centers and IT infrastructure monitoring, the potential for privilege escalation and data compromise increases significantly. The vulnerability could enable attackers to access monitoring dashboards, view network configurations, or manipulate monitoring alerts, potentially leading to undetected network intrusions or service disruptions.
Mitigation strategies for this DOM-based XSS vulnerability should focus on implementing proper input validation and output encoding practices throughout the application codebase. Developers should avoid using dangerous DOM methods that directly incorporate user input into JavaScript execution contexts and instead utilize safer alternatives such as textContent or createElement methods. The implementation of Content Security Policy headers can provide additional protection layers, while proper input sanitization libraries should be integrated to filter out malicious script patterns. Organizations should also implement regular security code reviews and automated scanning tools to identify similar vulnerabilities in their web applications. This vulnerability aligns with ATT&CK technique T1566 which covers social engineering tactics involving the exploitation of web application vulnerabilities, and T1071 which addresses application layer protocols that can be leveraged for malicious activities. The specific remediation approach should include comprehensive testing of all DOM-based input handling and implementation of a robust security development lifecycle that incorporates security testing at every stage of the application development process.