CVE-2018-25119 in Fusion
Summary
by MITRE • 10/31/2025
Nagios Fusion versions prior to 4.1.5 are vulnerable to cross-site scripting (XSS) via the "fusionwindow" parameter. 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.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 11/08/2025
Nagios Fusion represents a web-based monitoring solution that provides centralized management and visualization capabilities for network infrastructure monitoring. The vulnerability identified as CVE-2018-25119 affects versions prior to 4.1.5 and specifically targets the fusionwindow parameter within the application's web interface. This parameter is utilized to control the display and behavior of various monitoring windows and dashboards within the Fusion environment. The vulnerability arises from inadequate input validation mechanisms that fail to properly sanitize user-supplied data before processing and rendering within the browser context.
The technical flaw manifests as a classic cross-site scripting vulnerability where malicious input passed through the fusionwindow parameter can be executed within the victim's browser session. When users navigate to pages that utilize this parameter without proper sanitization, the application fails to escape special characters or validate the input against known malicious patterns. This allows attackers to inject JavaScript code that executes in the context of legitimate user sessions, potentially enabling session hijacking, credential theft, or redirection to malicious sites. The vulnerability falls under CWE-79 which specifically addresses cross-site scripting flaws in web applications, and aligns with ATT&CK technique T1059.007 for scripting languages.
The operational impact of this vulnerability extends beyond simple data exfiltration as it provides attackers with persistent access to monitored systems through compromised user sessions. An attacker could exploit this vulnerability to gain unauthorized access to sensitive monitoring data, potentially revealing network configurations, system vulnerabilities, and operational details that would otherwise remain protected. The attack surface is particularly concerning given that Nagios Fusion is commonly deployed in enterprise environments where it serves as a critical monitoring tool, making it an attractive target for adversaries seeking long-term access to network infrastructure. Organizations using older versions of this software face significant risk of unauthorized access to their monitoring dashboards and potentially sensitive operational data.
Mitigation strategies for CVE-2018-25119 focus primarily on upgrading to Nagios Fusion version 4.1.5 or later, which includes proper input validation and sanitization mechanisms for the fusionwindow parameter. Administrators should implement comprehensive input validation that filters out potentially malicious characters and employs proper output encoding when rendering user-supplied data. Additional protective measures include implementing content security policies that restrict script execution within the application, utilizing web application firewalls to detect and block malicious payloads, and conducting regular security assessments of web applications. Network segmentation and privileged access controls can further limit the potential impact of successful exploitation attempts, while user education about recognizing suspicious links and monitoring for unusual application behavior remains essential for comprehensive defense.