CVE-2019-25398: IPFire ovpnmain.cgi XSS Vulnerability

CVE-2019-25398 Overview

CVE-2019-25398 is a Cross-Site Scripting (XSS) vulnerability affecting IPFire 2.21 Core Update 127. The vulnerability exists within the ovpnmain.cgi script, which fails to properly sanitize user-supplied input across multiple VPN configuration parameters. Attackers can exploit this weakness by injecting malicious JavaScript payloads through POST requests, which are then executed in the context of an authenticated administrator's browser session.

Critical Impact

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

Affected Products

• IPFire 2.21 Core Update 127
• IPFire ovpnmain.cgi VPN configuration module

Discovery Timeline

• 2026-02-18 - CVE-2019-25398 published to NVD
• 2026-02-19 - Last updated in NVD database

Technical Details for CVE-2019-25398

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 ovpnmain.cgi script in IPFire's web interface processes multiple VPN configuration parameters without adequate input validation or output encoding. When administrators access pages that display these parameter values, any injected script content executes within the trusted security context of the IPFire administrative interface.

The attack requires user interaction—specifically, an administrator must visit or submit a page where the malicious payload is rendered. Because IPFire is a network firewall appliance, successful XSS exploitation could allow attackers to modify firewall rules, VPN configurations, or extract sensitive network topology information.

Root Cause

The root cause stems from insufficient input sanitization in the ovpnmain.cgi CGI script. The script accepts and processes multiple parameters related to OpenVPN configuration without properly encoding special characters before rendering them back to the user interface. Parameters including VPN_IP, DMTU, ccdname, ccdsubnet, DOVPN_SUBNET, DHCP_DOMAIN, DHCP_DNS, DHCP_WINS, ROUTES_PUSH, FRAGMENT, KEEPALIVE_1, and KEEPALIVE_2 all fail to escape HTML special characters, enabling script injection.

Attack Vector

The attack leverages the network-accessible web administration interface of IPFire. An attacker crafts a malicious POST request containing JavaScript payloads within one or more of the vulnerable VPN configuration parameters. This can be achieved through various means including social engineering an administrator to click a malicious link, or by exploiting another vulnerability that allows cross-origin requests.

When the administrator's browser processes the reflected or stored XSS payload, the malicious script executes with full access to the administrative session, potentially allowing the attacker to perform any action the administrator could, including modifying firewall rules or extracting VPN credentials.

For detailed exploitation techniques, refer to the Exploit-DB #46344 proof-of-concept documentation.

Detection Methods for CVE-2019-25398

Indicators of Compromise

• Unusual POST requests to /cgi-bin/ovpnmain.cgi containing script tags or JavaScript event handlers in parameter values
• Web server logs showing encoded JavaScript payloads (e.g., %3Cscript%3E, javascript:, onerror=, onload=) in VPN configuration parameters
• Unexpected changes to VPN or firewall configurations without corresponding administrator activity
• Administrator session anomalies such as multiple simultaneous sessions or sessions from unexpected IP addresses

Detection Strategies

• Deploy web application firewall (WAF) rules to detect and block XSS payloads in requests to IPFire CGI scripts
• Monitor HTTP POST requests to ovpnmain.cgi for suspicious parameter values containing HTML tags or JavaScript
• Implement intrusion detection signatures for known XSS attack patterns targeting IPFire administrative interfaces
• Configure alerting for configuration changes made outside of normal administrative windows

Monitoring Recommendations

• Enable verbose logging on the IPFire web server to capture full request parameters
• Regularly audit VPN configurations for unexpected or unauthorized entries
• Monitor administrator account activity and session logs for signs of session hijacking
• Review web access logs for repeated requests to CGI scripts with varying parameter values indicative of exploitation attempts

How to Mitigate CVE-2019-25398

Immediate Actions Required

• Upgrade IPFire to the latest available Core Update version that addresses this vulnerability
• Restrict administrative interface access to trusted networks only using firewall rules
• Implement network segmentation to isolate management interfaces from untrusted networks
• Enable multi-factor authentication if available for administrative access

Patch Information

IPFire users should upgrade to a Core Update version newer than 127 that includes proper input validation for the ovpnmain.cgi script. The latest IPFire releases are available from the IPFire Official Website. Review the VulnCheck Advisory on IPFire for additional remediation guidance.

Workarounds

• Restrict web interface access to localhost only and use SSH tunneling for administrative access
• Deploy a reverse proxy with XSS filtering capabilities in front of the IPFire web interface
• Disable the web-based OpenVPN configuration interface and manage VPN settings via command-line if operationally feasible
• Implement Content Security Policy (CSP) headers at the reverse proxy level to mitigate script execution

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