CVE-2020-36864 in Nagios
Summary
by MITRE • 10/31/2025
Nagios XI versions prior to 5.7.2 are vulnerable to cross-site scripting (XSS) via the background color settings in Dashboards. Insufficient validation or escaping of user-supplied input may allow an attacker to inject and execute arbitrary script in the context of a victim's browser.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 10/31/2025
Nagios XI is a comprehensive network monitoring and management platform that provides real-time visibility into network infrastructure performance and availability. The vulnerability described in CVE-2020-36864 specifically affects versions prior to 5.7.2 and represents a critical cross-site scripting flaw that undermines the security integrity of the dashboard functionality. This vulnerability resides within the background color settings configuration where users can customize dashboard appearance through web interface controls. The flaw allows attackers to manipulate the application's input handling mechanisms, creating a pathway for malicious script execution within victim browsers. The issue stems from inadequate sanitization of user-supplied parameters that are directly rendered in the dashboard context without proper HTML escaping or input validation measures.
The technical exploitation of this vulnerability occurs when an attacker crafts malicious input containing script code within the background color settings parameters. When the affected Nagios XI application processes this input without proper validation, the malicious code gets embedded into the dashboard HTML output and subsequently executed in the context of authenticated users' browsers. This creates a persistent threat vector where attackers can leverage the vulnerability to perform actions such as stealing session cookies, redirecting users to malicious sites, or executing arbitrary commands on behalf of authenticated users. The vulnerability is particularly dangerous because it operates within the administrative interface where users typically have elevated privileges, potentially allowing attackers to escalate their access level and compromise the entire monitoring infrastructure. According to CWE standards, this represents a classic cross-site scripting vulnerability classified under CWE-79, which specifically addresses improper neutralization of input during web page generation.
The operational impact of this vulnerability extends beyond simple script execution to encompass significant risks to network monitoring integrity and organizational security posture. An attacker who successfully exploits this vulnerability can gain access to sensitive monitoring data, potentially compromising the visibility of critical network infrastructure components. The attack surface is particularly concerning because Nagios XI dashboards often display real-time monitoring information including system status, performance metrics, and alert notifications that may contain sensitive operational data. Additionally, the vulnerability can be exploited to create persistent backdoors within the monitoring environment, allowing attackers to maintain long-term access to the network infrastructure. Organizations using affected versions may experience unauthorized access to their monitoring systems, leading to potential data breaches and loss of critical operational visibility. The vulnerability also aligns with ATT&CK technique T1566, specifically targeting credential access through malicious web content, and can be leveraged to establish initial access within the network monitoring environment.
Mitigation strategies for this vulnerability require immediate implementation of the vendor-provided patch for Nagios XI version 5.7.2 or later, which addresses the input validation and escaping mechanisms within the dashboard color settings functionality. Organizations should implement comprehensive input validation at multiple layers including application-level sanitization of all user-supplied parameters and proper HTML escaping of dynamic content rendered in web interfaces. Network administrators should also consider implementing additional security controls such as web application firewalls that can detect and block malicious script injection attempts. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities within the monitoring infrastructure. The vulnerability highlights the importance of maintaining up-to-date security patches and implementing defense-in-depth strategies for critical monitoring systems. Organizations should also establish robust monitoring procedures to detect unauthorized modifications to dashboard configurations and implement role-based access controls to limit the potential impact of successful exploitation attempts.