CVE-2019-25427: Comodo Dome Firewall XSS Vulnerability

CVE-2019-25427 Overview

Comodo Dome Firewall 2.7.0 contains a reflected cross-site scripting (XSS) vulnerability that allows attackers to inject malicious scripts by submitting crafted input to the antispyware endpoint. This vulnerability enables attackers to send POST requests with JavaScript payloads in the DNSMASQ_WHITELIST or DNSMASQ_BLACKLIST parameters to execute arbitrary code in users' browsers.

Critical Impact

Attackers can exploit this XSS vulnerability to steal session cookies, perform unauthorized actions on behalf of authenticated administrators, redirect users to malicious sites, or inject malware through the firewall management interface.

Affected Products

• Comodo Dome Firewall version 2.7.0
• Comodo Dome Firewall antispyware module

Discovery Timeline

• 2026-02-19 - CVE CVE-2019-25427 published to NVD
• 2026-02-19 - Last updated in NVD database

Technical Details for CVE-2019-25427

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting (XSS). The reflected XSS flaw exists in the antispyware endpoint of Comodo Dome Firewall 2.7.0, where user-supplied input is not properly sanitized before being included in the HTTP response.

The vulnerability affects the DNSMASQ_WHITELIST and DNSMASQ_BLACKLIST parameters, which accept DNS filtering rules as input. When an attacker submits a malicious JavaScript payload through these parameters, the application reflects the unsanitized input back to the user's browser, causing the script to execute in the context of the authenticated session.

This is a network-accessible vulnerability that requires user interaction (such as clicking a malicious link) to be exploited successfully.

Root Cause

The root cause of this vulnerability is insufficient input validation and output encoding in the Comodo Dome Firewall's antispyware endpoint. The application fails to properly sanitize user-controlled input in the DNSMASQ_WHITELIST and DNSMASQ_BLACKLIST parameters before including them in the HTTP response. Without proper HTML entity encoding or input filtering, malicious JavaScript code embedded in these parameters is rendered and executed by the victim's browser.

Attack Vector

The attack vector involves an attacker crafting a malicious URL or POST request containing JavaScript payloads in the vulnerable parameters. The attacker must then socially engineer an authenticated administrator into clicking the malicious link or submitting the crafted form. When the victim's browser processes the response, the injected script executes with the same privileges as the authenticated user.

The attack flow involves: (1) crafting a POST request with a JavaScript payload in the DNSMASQ_WHITELIST or DNSMASQ_BLACKLIST parameter, (2) delivering the malicious request to a victim through phishing or other social engineering techniques, and (3) the victim's browser executing the attacker's JavaScript code when processing the reflected response.

For technical details and proof-of-concept information, refer to the Exploit-DB #46408 entry and the VulnCheck Comodo Dome Advisory.

Detection Methods for CVE-2019-25427

Indicators of Compromise

• Unusual POST requests to the antispyware endpoint containing JavaScript or HTML tags in the DNSMASQ_WHITELIST or DNSMASQ_BLACKLIST parameters
• Web server logs showing encoded script tags (<script>, %3Cscript%3E, or similar) in request parameters
• Browser console errors or unexpected JavaScript execution on the firewall management interface
• Reports from administrators of unusual redirect behavior or session issues after accessing management URLs

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block requests containing common XSS payloads in POST parameters
• Configure intrusion detection systems (IDS) to alert on HTTP traffic containing suspicious JavaScript patterns targeting the antispyware endpoint
• Enable detailed logging on the Comodo Dome Firewall web interface and review for anomalous input patterns
• Deploy browser-based XSS detection tools for administrators accessing the firewall management console

Monitoring Recommendations

• Monitor web server access logs for requests to the antispyware endpoint with abnormal parameter values
• Set up alerting for any HTTP responses containing user-controlled input without proper encoding
• Track failed Content Security Policy (CSP) violations if implemented on the management interface
• Review administrator session activity for signs of unauthorized actions following suspicious access patterns

How to Mitigate CVE-2019-25427

Immediate Actions Required

• Restrict access to the Comodo Dome Firewall management interface to trusted IP addresses only
• Implement network segmentation to limit exposure of the firewall's administrative web interface
• Educate administrators about the risks of clicking untrusted links while authenticated to the firewall console
• Consider deploying a reverse proxy with XSS filtering in front of the management interface as an interim measure

Patch Information

No specific patch information is available from the vendor in the provided data. Organizations should check the Comodo Firewall product page for the latest security updates and upgrade to the most recent version of Comodo Dome Firewall that addresses this vulnerability.

Workarounds

• Implement strict Content Security Policy (CSP) headers on the firewall management interface to prevent inline script execution
• Use a web application firewall (WAF) to filter incoming requests for XSS payloads before they reach the firewall management interface
• Limit administrative access to the firewall management console to a dedicated management network or VPN
• Require multi-factor authentication for firewall administrative access to reduce the impact of session compromise
• Disable or restrict access to the antispyware endpoint if the functionality is not required

# Example: Restrict access to management interface via iptables
# Replace 192.168.1.0/24 with your trusted management network
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP