CVE-2026-28771: IDC SuperFlex Receiver XSS Vulnerability

CVE-2026-28771 Overview

A Reflected Cross-Site Scripting (XSS) vulnerability exists in the /index.cgi endpoint of International Datacasting Corporation (IDC) SFX Series SuperFlex Satellite Receiver Web Management Interface version 101. The application fails to adequately sanitize user-supplied input provided via the cat parameter before reflecting it in the HTTP response, allowing a remote attacker to execute arbitrary HTML or JavaScript in the victim's browser context.

Critical Impact

Attackers can execute arbitrary JavaScript in authenticated user sessions, potentially leading to session hijacking, credential theft, or unauthorized administrative actions on satellite receiver infrastructure.

Affected Products

• International Datacasting Corporation (IDC) SFX Series SuperFlex Satellite Receiver
• Web Management Interface version 101
• /index.cgi endpoint with cat parameter

Discovery Timeline

• 2026-03-04 - CVE-2026-28771 published to NVD
• 2026-03-05 - Last updated in NVD database

Technical Details for CVE-2026-28771

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting. The IDC SuperFlex Satellite Receiver's web management interface contains a reflected XSS flaw in the /index.cgi endpoint. When processing HTTP requests, the application directly incorporates the value of the cat query parameter into the response without proper output encoding or input validation.

The network-accessible attack vector requires user interaction, as a victim must be tricked into clicking a malicious link or visiting an attacker-controlled page that redirects to the vulnerable endpoint. Once triggered, the injected script executes within the security context of the victim's browser session with the satellite receiver management interface.

Root Cause

The root cause is insufficient input sanitization in the web management interface's CGI handler. The cat parameter value is reflected directly into the HTTP response body without encoding special characters such as <, >, ", and '. This allows attackers to break out of the intended HTML context and inject arbitrary script content that the browser interprets as legitimate code from the application.

Attack Vector

An attacker can craft a malicious URL containing JavaScript payload in the cat parameter. When a victim with an active session to the satellite receiver management interface clicks this link, the malicious script executes in their browser context. This could enable session token theft, keylogging of credentials entered into the interface, or performing administrative actions on behalf of the victim such as modifying satellite receiver configurations.

The vulnerability is exploitable by sending a specially crafted HTTP request to the /index.cgi endpoint where the cat parameter contains HTML or JavaScript code. For detailed technical analysis, refer to the Abdul MHS Blog Vulnerability Post.

Detection Methods for CVE-2026-28771

Indicators of Compromise

• HTTP requests to /index.cgi containing script tags or JavaScript event handlers in the cat parameter
• Unusual patterns in web server logs showing encoded characters like %3Cscript%3E or %22onload%3D in query strings
• Browser console errors or unexpected script execution when accessing the management interface
• Outbound connections from client browsers to unknown domains after accessing the receiver interface

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block common XSS patterns in the cat parameter
• Deploy network intrusion detection signatures for reflected XSS payloads targeting /index.cgi
• Monitor web server access logs for requests containing suspicious characters or encoding patterns in query parameters
• Use browser-based security tools to detect script injection attempts on management interfaces

Monitoring Recommendations

• Enable verbose logging on the satellite receiver web management interface to capture full request details
• Set up alerts for HTTP requests to /index.cgi with query strings exceeding normal length or containing special characters
• Monitor for any unusual administrative actions that could indicate compromised sessions
• Implement Content Security Policy (CSP) headers to detect and report inline script execution violations

How to Mitigate CVE-2026-28771

Immediate Actions Required

• Restrict network access to the web management interface using firewall rules or VPN requirements
• Implement IP allowlisting to limit access to trusted administrative workstations only
• Educate administrators about the risks of clicking untrusted links while authenticated to the management interface
• Consider disabling the web management interface if not actively required for operations

Patch Information

No vendor patch information is currently available in the CVE data. Monitor International Datacasting Corporation's official channels for security updates. Additional technical details about this vulnerability are documented in the external security research post.

Workarounds

• Deploy a reverse proxy with XSS filtering capabilities in front of the management interface
• Implement network segmentation to isolate the satellite receiver management interface from general user networks
• Use browser extensions that provide additional XSS protection when accessing the management interface
• Configure HTTP response headers including X-XSS-Protection, X-Content-Type-Options, and strict Content-Security-Policy at the network edge

# Example: Restrict access to management interface using iptables
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP

# Example: Add security headers via reverse proxy (nginx)
add_header X-XSS-Protection "1; mode=block" always;
add_header X-Content-Type-Options "nosniff" always;
add_header Content-Security-Policy "default-src 'self'; script-src 'self'" always;