CVE-2019-25430: Comodo Dome Firewall XSS Vulnerability

CVE-2019-25430 Overview

CVE-2019-25430 is a reflected cross-site scripting (XSS) vulnerability affecting Comodo Dome Firewall version 2.7.0. The vulnerability allows unauthenticated attackers to inject malicious scripts by submitting crafted input to the username parameter. Attackers can exploit this flaw by sending POST requests to the vpn_users endpoint with script payloads in the username field, enabling the execution of arbitrary JavaScript code in victim browsers.

Critical Impact

Unauthenticated attackers can execute arbitrary JavaScript in the context of authenticated user sessions, potentially leading to session hijacking, credential theft, or administrative account compromise on the firewall management interface.

Affected Products

• Comodo Dome Firewall 2.7.0
• comodo dome_firewall (cpe:2.3:a:comodo:dome_firewall:2.7.0:::::::*)

Discovery Timeline

• 2026-02-19 - CVE CVE-2019-25430 published to NVD
• 2026-02-19 - Last updated in NVD database

Technical Details for CVE-2019-25430

Vulnerability Analysis

This reflected cross-site scripting vulnerability exists in the VPN users management functionality of Comodo Dome Firewall. The application fails to properly sanitize user-supplied input in the username parameter before reflecting it back in the HTTP response. When an attacker crafts a malicious request containing JavaScript code within this parameter and tricks a victim into clicking the link or submitting the form, the malicious script executes within the victim's browser session.

The network-accessible attack vector means this vulnerability can be exploited remotely without authentication. However, successful exploitation requires user interaction—a victim must be enticed to click a malicious link or submit a crafted form. The vulnerability primarily impacts the integrity of user sessions within the firewall management interface.

Root Cause

The root cause of CVE-2019-25430 is improper input validation and insufficient output encoding (CWE-79). The vpn_users endpoint accepts the username parameter in POST requests without adequately sanitizing or encoding special characters. When this unsanitized input is reflected back into the HTML response, malicious script content is rendered as executable code rather than harmless text.

Attack Vector

The attack leverages the network-accessible vpn_users endpoint in Comodo Dome Firewall. An attacker constructs a malicious POST request containing JavaScript code within the username parameter. This can be delivered through various social engineering techniques:

1. Embedding the malicious payload in a crafted HTML form hosted on an attacker-controlled site
2. Using phishing emails containing links that auto-submit forms to the vulnerable endpoint
3. Leveraging other vulnerabilities to redirect users to the malicious payload

When a victim with an active session to the Comodo Dome Firewall management interface triggers the malicious request, the injected JavaScript executes with the victim's session privileges, potentially allowing session token theft, privilege escalation, or unauthorized configuration changes.

Technical details and proof-of-concept information can be found in the Exploit-DB #46408 entry and the VulnCheck Comodo Dome Advisory.

Detection Methods for CVE-2019-25430

Indicators of Compromise

• Suspicious POST requests to the vpn_users endpoint containing script tags or JavaScript event handlers in the username parameter
• Web server logs showing encoded characters such as %3Cscript%3E or %22onmouseover%3D in request parameters
• Unusual outbound connections from administrator workstations following access to the firewall management interface
• Browser console errors or unexpected script execution warnings in firewall admin sessions

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block XSS payloads in POST request parameters targeting the vpn_users endpoint
• Configure intrusion detection systems (IDS) to alert on patterns matching common XSS attack signatures in HTTP traffic to the Comodo Dome Firewall management interface
• Enable detailed logging on the firewall management interface and monitor for anomalous parameter values
• Deploy browser-based security controls and Content Security Policy headers to prevent inline script execution

Monitoring Recommendations

• Review web server access logs for the vpn_users endpoint, filtering for requests with suspicious character sequences in the username field
• Monitor network traffic for POST requests to the firewall management interface from external or unexpected source addresses
• Implement session monitoring to detect unusual session activity following potential XSS exploitation attempts
• Set up alerts for multiple failed or suspicious authentication-related requests to the firewall management interface

How to Mitigate CVE-2019-25430

Immediate Actions Required

• Restrict access to the Comodo Dome Firewall management interface to trusted internal networks only
• Implement network segmentation to isolate the firewall management interface from general user traffic
• Deploy a web application firewall (WAF) in front of the management interface with XSS protection rules enabled
• Educate administrators about phishing risks and suspicious links targeting firewall management systems
• Consider disabling or restricting access to the vpn_users functionality until a patch is applied

Patch Information

No vendor patch information is currently available in the CVE data. Organizations should contact Comodo support directly for guidance on security updates. Monitor the Comodo Dome Firewall product page for security advisories and firmware updates that address this vulnerability.

Workarounds

• Configure firewall rules to limit management interface access to specific trusted IP addresses only
• Implement Content Security Policy (CSP) headers at the reverse proxy or load balancer level to mitigate XSS impact
• Use browser extensions or enterprise policies that block inline JavaScript execution on the management interface
• Require multi-factor authentication for all administrative access to reduce the impact of potential session hijacking

# Example: Restrict management interface access using iptables
# Allow management access only from trusted admin network
iptables -A INPUT -p tcp --dport 443 -s 10.0.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP