CVE-2023-4981 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 web applications represent one of the most prevalent and dangerous security flaws encountered in modern software systems. The specific vulnerability identified in the librenms/librenms repository affects versions prior to 23.9.0 and manifests as a DOM-based cross-site scripting issue that exploits client-side script execution mechanisms. This particular vulnerability falls under the CWE-79 category, which specifically addresses cross-site scripting flaws in web applications where malicious scripts can be injected into web pages viewed by other users. The DOM-based nature of this vulnerability means that the attack vector operates entirely within the client-side environment without requiring server-side modifications to the application's source code.
The technical flaw in this implementation stems from inadequate input validation and sanitization of data passed through DOM elements, particularly within the JavaScript execution context of the web application. When user-supplied data flows through the DOM without proper sanitization, attackers can inject malicious scripts that execute in the context of other users' browsers. This type of vulnerability is particularly concerning because it can be exploited through various attack vectors including URL parameters, form inputs, or even cookies that are processed by JavaScript functions. The vulnerability exists in the application's client-side processing logic where dynamic content is constructed from user-provided inputs without appropriate security measures to prevent script injection.
The operational impact of this vulnerability extends beyond simple data theft or session hijacking, as it can enable attackers to perform actions on behalf of authenticated users within the application context. An attacker could potentially escalate privileges, modify configuration settings, or gain access to sensitive network monitoring data that the application is designed to protect. This is particularly dangerous in network monitoring environments like LibreNMS, where the application typically handles critical infrastructure data and may provide administrative access to network devices. The vulnerability could allow for complete compromise of the monitoring environment, potentially leading to unauthorized access to network devices, data exfiltration, or disruption of network services.
The exploitation of this DOM-based XSS vulnerability typically involves crafting malicious URLs or input parameters that, when processed by the vulnerable JavaScript code, execute unintended scripts in the victim's browser. The ATT&CK framework categorizes this type of vulnerability under T1531 - Account Access Token Manipulation, as successful exploitation can lead to unauthorized access to user accounts and privileges. Mitigation strategies should focus on implementing comprehensive input validation, output encoding, and Content Security Policy (CSP) headers to prevent script execution in unexpected contexts. The recommended approach includes updating to version 23.9.0 or later, which contains the necessary patches to address the DOM-based XSS vulnerability, along with implementing proper sanitization of all user inputs before they are processed by client-side JavaScript functions. Additionally, organizations should consider implementing web application firewalls and regular security testing to identify similar vulnerabilities in their web applications.
The vulnerability demonstrates the critical importance of proper security testing and code review processes in web application development. DOM-based XSS vulnerabilities are particularly challenging to detect through traditional static analysis tools because they often require dynamic analysis of how data flows through JavaScript code. This particular flaw in the LibreNMS application highlights the need for comprehensive security practices including threat modeling, secure coding guidelines, and regular penetration testing to identify and remediate such vulnerabilities before they can be exploited in production environments. Organizations using similar monitoring and management platforms should conduct immediate assessments to identify any instances of this vulnerability within their deployments and implement appropriate mitigations as outlined in the vendor's security advisories.