CVE-2025-40894: Nozomi Networks CMC XSS Vulnerability

CVE-2025-40894 Overview

A Stored HTML Injection vulnerability has been identified in the Alerted Nodes Dashboard functionality of Nozomi Networks Guardian and CMC platforms. The vulnerability stems from improper validation on an input parameter, allowing authenticated users with appropriate privileges to inject malicious HTML tags through node label editing.

When the system is configured to use the Alerted Nodes Dashboard and alerts are reported for the affected node, the injected HTML renders in the browser of victim users interacting with the dashboard. This enables phishing attacks and potentially open redirect scenarios. The existing input validation and Content Security Policy (CSP) configuration prevents full Cross-Site Scripting (XSS) exploitation and direct information disclosure.

Critical Impact

Authenticated attackers can inject HTML content into node labels, enabling phishing and open redirect attacks against other users viewing the Alerted Nodes Dashboard.

Affected Products

• Nozomi Networks CMC (all versions prior to patched release)
• Nozomi Networks Guardian (all versions prior to patched release)

Discovery Timeline

• 2026-03-04 - CVE-2025-40894 published to NVD
• 2026-03-05 - Last updated in NVD database

Technical Details for CVE-2025-40894

Vulnerability Analysis

This vulnerability falls under CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting. The flaw exists in the Alerted Nodes Dashboard where node labels are not properly sanitized before being rendered in the web interface.

The attack requires an authenticated user with privileges to edit node labels. Once malicious HTML is injected into a node label, it persists in the system (stored injection) and executes when other users view the affected node in the Alerted Nodes Dashboard. The network-based attack vector with high complexity requirements and the need for user interaction reduces the overall exploitability.

While the vulnerability enables HTML injection, the application's existing security controls—including input validation mechanisms and Content Security Policy headers—effectively prevent escalation to full XSS attacks. This limits the attack to phishing scenarios where injected HTML could present fake login forms or misleading content, and open redirect attacks that could redirect users to malicious external sites.

Root Cause

The root cause is insufficient input validation on the node label parameter within the Alerted Nodes Dashboard functionality. The application fails to properly sanitize or encode user-supplied input before storing and subsequently rendering it in the web interface. While some validation exists that prevents full script execution, it does not adequately filter HTML markup, allowing attackers to inject structural HTML elements.

Attack Vector

The attack follows a network-based vector requiring the attacker to have authenticated access with privileges to modify node labels. The exploitation process involves:

1. An authenticated attacker edits a node label within the management interface
2. The attacker injects HTML tags into the node label field
3. The malicious content is stored in the system database
4. When the system generates alerts for the affected node, the injected HTML renders in the Alerted Nodes Dashboard
5. Victim users viewing the dashboard see the rendered HTML content, which can present phishing content or redirect links

The attack complexity is considered high due to the multiple prerequisites: the attacker needs authentication with specific privileges, the system must be configured to use the Alerted Nodes Dashboard, alerts must be generated for the targeted node, and victim users must interact with the dashboard.

Detection Methods for CVE-2025-40894

Indicators of Compromise

• Unusual HTML tags present in node label fields within the database or configuration files
• Node labels containing suspicious content such as <a>, <form>, <iframe>, or <img> tags
• Reports from users about unexpected visual elements or prompts appearing in the Alerted Nodes Dashboard

Detection Strategies

• Implement database queries to scan node label fields for HTML tag patterns
• Review audit logs for node label modification events, particularly from users with elevated privileges
• Deploy web application firewall rules to detect HTML injection patterns in input fields
• Enable browser developer tools monitoring for unexpected DOM elements during dashboard interaction

Monitoring Recommendations

• Enable comprehensive audit logging for all node label modification operations
• Configure alerting for any node labels containing angle bracket characters (< and >)
• Monitor user session activity for privilege escalation attempts followed by node configuration changes
• Implement regular security reviews of stored node configuration data

How to Mitigate CVE-2025-40894

Immediate Actions Required

• Review all existing node labels for injected HTML content and sanitize any suspicious entries
• Restrict node label editing privileges to trusted administrators only
• Temporarily disable the Alerted Nodes Dashboard if phishing concerns are elevated
• Educate users to report any suspicious visual elements appearing in the dashboard interface

Patch Information

Nozomi Networks has released a security advisory addressing this vulnerability. Administrators should consult the Nozomi Networks Security Advisory NN-2025:16-01 for detailed patch information and upgrade instructions for both Guardian and CMC platforms. Apply the vendor-provided patches as soon as they become available for your deployment.

Workarounds

• Implement strict access control policies limiting node label editing to essential personnel only
• Deploy additional input validation at the network level using a web application firewall
• Review and strengthen Content Security Policy headers to further restrict content rendering capabilities
• Conduct regular audits of node label contents to identify and remove any injected HTML

# Example: Search for potential HTML injection in node labels (adjust for your environment)
# This command searches log files for HTML tag patterns in label-related entries
grep -E '<[a-zA-Z]+[^>]*>' /var/log/nozomi/audit.log | grep -i "label"