CVE-2019-25400: IPFire 2.21 Core XSS Vulnerability

CVE-2019-25400 Overview

CVE-2019-25400 is a reflected cross-site scripting (XSS) vulnerability affecting IPFire 2.21 Core Update 127. The vulnerability exists in the fwhosts.cgi script, which fails to properly sanitize user-supplied input across multiple parameters. This allows attackers to inject malicious JavaScript code that executes in the context of authenticated users' browsers, potentially leading to session hijacking, credential theft, or unauthorized actions on behalf of legitimate administrators.

Critical Impact

Attackers can exploit this XSS vulnerability to execute arbitrary JavaScript in authenticated users' browsers, potentially compromising firewall administrator sessions and enabling further attacks against network infrastructure.

Affected Products

• IPFire 2.21 Core Update 127
• IPFire firewall appliances running vulnerable fwhosts.cgi script

Discovery Timeline

• 2026-02-18 - CVE-2019-25400 published to NVD
• 2026-02-19 - Last updated in NVD database

Technical Details for CVE-2019-25400

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as reflected cross-site scripting. The fwhosts.cgi script in IPFire's web management interface processes user input from POST requests without adequate sanitization or output encoding.

Multiple parameters are vulnerable to script injection, including HOSTNAME, IP, SUBNET, NETREMARK, HOSTREMARK, newhost, grp_name, remark, SRV_NAME, SRV_PORT, SRVGRP_NAME, SRVGRP_REMARK, and updatesrvgrp. When an attacker crafts a malicious request containing JavaScript payloads in any of these parameters, the script reflects the unsanitized input back to the user's browser, causing the injected code to execute.

The attack requires user interaction, as the victim must be tricked into clicking a malicious link or submitting a crafted form while authenticated to the IPFire web interface.

Root Cause

The root cause of this vulnerability is inadequate input validation and output encoding in the fwhosts.cgi script. The CGI script directly incorporates user-supplied data into HTML responses without properly escaping special characters such as angle brackets (<, >), quotation marks, and other HTML metacharacters. This allows attackers to break out of the intended HTML context and inject executable script content.

Attack Vector

The attack vector is network-based and requires low privileges but active user interaction. An attacker can exploit this vulnerability by:

1. Crafting a malicious POST request containing JavaScript payloads in one or more vulnerable parameters
2. Convincing an authenticated IPFire administrator to click a link that triggers the malicious request
3. The reflected script executes in the victim's browser session with the same privileges as the authenticated user

Successful exploitation could allow attackers to steal session cookies, perform actions as the administrator, modify firewall rules, or redirect users to malicious websites.

The vulnerability is documented in Exploit-DB #46344, which contains proof-of-concept details. Additional technical information is available in the VulnCheck Advisory for IPFire.

Detection Methods for CVE-2019-25400

Indicators of Compromise

• Unusual POST requests to /cgi-bin/fwhosts.cgi containing JavaScript code or HTML tags in parameter values
• Web server logs showing requests with encoded script content (e.g., %3Cscript%3E) in vulnerable parameters
• Unexpected session activity or administrative actions following user access to suspicious links

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block XSS payloads in requests to fwhosts.cgi
• Monitor HTTP POST requests for suspicious patterns including <script>, javascript:, event handlers like onerror=, and other XSS vectors
• Review web server access logs for anomalous requests targeting the vulnerable CGI script with encoded special characters

Monitoring Recommendations

• Enable verbose logging for the IPFire web management interface to capture full request parameters
• Configure intrusion detection systems to alert on XSS attack signatures targeting CGI scripts
• Establish baseline behavior for administrative sessions and alert on deviations such as unexpected source IPs or user agents

How to Mitigate CVE-2019-25400

Immediate Actions Required

• Upgrade IPFire to a version newer than 2.21 Core Update 127 that includes proper input sanitization
• Restrict access to the IPFire web management interface to trusted networks only
• Implement a web application firewall to filter malicious input before it reaches the CGI script
• Educate administrators about the risks of clicking untrusted links while authenticated to the firewall interface

Patch Information

Users should upgrade to a patched version of IPFire that addresses the XSS vulnerabilities in the fwhosts.cgi script. The latest releases can be obtained from the IPFire Official Website. Review the IPFire ISO Release page for version history and apply the most current security updates.

Workarounds

• Limit access to the IPFire web interface to specific trusted IP addresses or networks using firewall rules
• Use a dedicated browser profile or session for IPFire administration that is not used for general web browsing
• Consider disabling the web interface entirely and managing IPFire via SSH command line if XSS concerns cannot be otherwise mitigated

# Example: Restrict web interface access to management network only
# Add to /etc/sysconfig/firewall.local or equivalent
iptables -A INPUT -p tcp --dport 444 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 444 -j DROP