CVE-2019-25422: Comodo Dome Firewall XSS Vulnerability

CVE-2019-25422 Overview

Comodo Dome Firewall 2.7.0 contains cross-site scripting (XSS) vulnerabilities that allow attackers to inject malicious scripts through the vpnfw endpoint. Attackers can submit POST requests with script payloads in the target parameter for reflected XSS or the remark parameter for stored XSS to execute arbitrary JavaScript in administrator browsers.

Critical Impact

Successful exploitation allows attackers to execute arbitrary JavaScript in the context of authenticated administrator sessions, potentially leading to session hijacking, credential theft, or unauthorized firewall configuration changes.

Affected Products

• Comodo Dome Firewall 2.7.0
• Comodo Dome Firewall versions prior to patched release

Discovery Timeline

• 2026-02-19 - CVE-2019-25422 published to NVD
• 2026-02-19 - Last updated in NVD database

Technical Details for CVE-2019-25422

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting. The Comodo Dome Firewall web management interface fails to properly sanitize user-supplied input before rendering it in the browser context.

The vulnerability manifests in two distinct forms within the vpnfw endpoint. The reflected XSS variant occurs when attacker-controlled data in the target parameter is immediately echoed back to the user without proper encoding. The stored XSS variant is more severe, as malicious payloads injected through the remark parameter are persisted in the application's database and executed whenever an administrator views the affected page.

Network-based exploitation requires no prior authentication, though successful attack execution depends on user interaction—specifically, an administrator must access the malicious payload either through a crafted link (reflected) or by viewing the compromised interface element (stored).

Root Cause

The root cause of this vulnerability is insufficient input validation and output encoding in the Comodo Dome Firewall web interface. The application accepts user-controlled data through POST request parameters without properly sanitizing special characters used in HTML and JavaScript contexts. When this unsanitized data is rendered in the administrative interface, the browser interprets the malicious content as legitimate code rather than data.

Attack Vector

The attack vector is network-based, requiring an attacker to craft malicious HTTP POST requests targeting the vpnfw endpoint. For reflected XSS attacks, the attacker must convince an authenticated administrator to click a specially crafted link or submit a manipulated form. For stored XSS attacks, once the malicious payload is injected into the remark field, it executes automatically whenever any administrator accesses the affected page, making this variant particularly dangerous in multi-administrator environments.

The vulnerability can be exploited without authentication to inject the payload, but the impact depends on the victim administrator's session context. Successful exploitation could allow attackers to steal session cookies, perform actions on behalf of the administrator, modify firewall rules, or redirect the administrator to malicious sites.

Detection Methods for CVE-2019-25422

Indicators of Compromise

• Unusual POST requests to the vpnfw endpoint containing script tags, event handlers, or JavaScript code in the target or remark parameters
• Suspicious HTML entities or encoded JavaScript patterns such as <script>, javascript:, or event attributes like onerror, onload in firewall logs
• Unexpected administrative actions or configuration changes that administrators did not initiate
• Reports from administrators of unusual browser behavior or unexpected redirects when accessing the firewall interface

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block XSS payloads in POST requests to the firewall management interface
• Enable detailed HTTP request logging on the Comodo Dome Firewall and monitor for suspicious patterns in the target and remark parameters
• Deploy browser-based Content Security Policy (CSP) monitoring to detect inline script execution attempts
• Use SentinelOne Singularity platform to monitor for unusual network traffic patterns and browser-based script injection attempts

Monitoring Recommendations

• Configure alerts for POST requests to the vpnfw endpoint containing common XSS payload signatures
• Monitor administrator session activity for signs of hijacking such as simultaneous logins from different IP addresses or geographic locations
• Review firewall configuration change logs regularly for unauthorized modifications
• Implement real-time alerting on any JavaScript execution anomalies within the administrative interface

How to Mitigate CVE-2019-25422

Immediate Actions Required

• Restrict access to the Comodo Dome Firewall administrative interface to trusted IP addresses only using network-level access controls
• Implement a reverse proxy with XSS filtering capabilities in front of the firewall management interface
• Educate administrators about the risks of clicking unknown links while authenticated to the firewall console
• Consider temporarily disabling external access to the management interface until a patch is applied

Patch Information

Refer to the VulnCheck Comodo Dome Advisory for the latest information on available patches and vendor guidance. Additional technical details about the vulnerability can be found on Exploit-DB #46408. Visit the Comodo Firewall Overview page to check for updated firmware versions that address this vulnerability.

Workarounds

• Implement strict Content Security Policy (CSP) headers on the firewall web interface to prevent inline script execution
• Deploy a web application firewall (WAF) rule to sanitize or block requests containing script tags and JavaScript event handlers
• Use browser extensions that block XSS attacks as an additional layer of defense for administrators
• Restrict administrative access to a dedicated management network segment isolated from general user traffic

# Configuration example - Implement IP-based access restrictions
# Add to firewall access control list to limit management interface access
# Example iptables rule to restrict management interface access
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP

# Example nginx reverse proxy CSP header configuration
# Add to nginx server block protecting the management interface
add_header Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none';" always;