CVE-2019-25397: IPFire XSS Vulnerability in hosts.cgi

CVE-2019-25397 Overview

CVE-2019-25397 is a reflected Cross-Site Scripting (XSS) vulnerability affecting IPFire 2.21 Core Update 127. The vulnerability exists in the hosts.cgi script, which fails to properly validate and sanitize user-supplied input in multiple parameters. Attackers can exploit this weakness by crafting malicious POST requests containing JavaScript payloads in the KEY1, IP, HOST, or DOM parameters, enabling arbitrary script execution in the context of authenticated users' browsers.

Critical Impact

Successful exploitation allows attackers to execute arbitrary JavaScript code in victims' browsers, potentially leading to session hijacking, credential theft, or unauthorized actions performed on behalf of authenticated administrators.

Affected Products

• IPFire 2.21 Core Update 127
• IPFire 2.x versions prior to patched releases

Discovery Timeline

• 2026-02-18 - CVE CVE-2019-25397 published to NVD
• 2026-02-19 - Last updated in NVD database

Technical Details for CVE-2019-25397

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as reflected Cross-Site Scripting (XSS). The hosts.cgi script in the IPFire web interface accepts user input through multiple POST parameters without implementing proper input validation or output encoding. When these unsanitized values are reflected back to the user's browser within the HTML response, any embedded JavaScript code executes within the security context of the IPFire management interface.

The attack requires user interaction, as the victim must be tricked into submitting a malicious request or clicking a crafted link. However, since IPFire serves as a firewall/router appliance with administrative capabilities, successful exploitation against an authenticated administrator could have significant security implications for the protected network.

Root Cause

The root cause of this vulnerability is insufficient input validation and output encoding in the hosts.cgi CGI script. The script processes POST request parameters (KEY1, IP, HOST, DOM) and reflects them in the HTTP response without sanitizing HTML special characters or implementing Content Security Policy headers. This allows script tags and event handlers embedded in parameter values to be interpreted as executable code by the victim's browser.

Attack Vector

The attack is network-based and requires the attacker to craft a malicious request targeting the hosts.cgi endpoint. The attacker must entice an authenticated IPFire administrator to either click a malicious link or submit a form containing the XSS payload. This can be accomplished through phishing emails, watering hole attacks, or social engineering techniques.

The malicious payload is submitted via POST request to the vulnerable CGI script. When the script processes the request and generates the response page, the unsanitized input is included in the HTML output, causing the browser to execute the attacker's JavaScript code. This code runs with the same privileges as the authenticated user session, potentially allowing the attacker to steal session cookies, modify firewall rules, or perform other administrative actions.

Technical details and proof-of-concept information are available in the Exploit-DB #46344 entry.

Detection Methods for CVE-2019-25397

Indicators of Compromise

• Unusual POST requests to /cgi-bin/hosts.cgi containing script tags or JavaScript event handlers
• Web server logs showing encoded or obfuscated JavaScript in KEY1, IP, HOST, or DOM parameters
• Reports from users about unexpected browser behavior when accessing the IPFire web interface

Detection Strategies

• Deploy Web Application Firewall (WAF) rules to detect and block XSS payloads in HTTP requests targeting CGI scripts
• Enable detailed logging on the IPFire web interface and monitor for suspicious parameter patterns
• Implement browser-based XSS auditing and Content Security Policy headers where possible
• Use intrusion detection signatures to identify common XSS attack patterns in network traffic

Monitoring Recommendations

• Monitor web server access logs for requests containing <script>, javascript:, onerror=, or similar XSS indicators
• Set up alerts for anomalous POST requests to administrative CGI endpoints
• Review authentication logs for session anomalies following suspicious web requests

How to Mitigate CVE-2019-25397

Immediate Actions Required

• Upgrade IPFire to the latest available Core Update that addresses this vulnerability
• Restrict access to the IPFire web management interface to trusted networks only
• Implement network segmentation to limit exposure of the administrative interface
• Educate administrators about phishing and social engineering tactics used to exploit XSS vulnerabilities

Patch Information

Users should upgrade to a patched version of IPFire that includes proper input validation and output encoding for the hosts.cgi script. The latest releases are available from the IPFire Official Website. Review the VulnCheck Advisory on IPFire for additional guidance on affected versions and remediation steps.

Workarounds

• Restrict administrative interface access to specific trusted IP addresses using firewall rules
• Access the IPFire web interface only through a dedicated management network or VPN
• Use browser extensions that block or sanitize potentially malicious scripts
• Disable JavaScript in browsers when accessing the administrative interface (may limit functionality)

# Example: Restrict web interface access to management VLAN only
# Add to IPFire firewall rules (adjust IP ranges as needed)
iptables -A INPUT -p tcp --dport 444 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 444 -j DROP