CVE-2026-28770: IDC SuperFlex Receiver XXE Vulnerability

CVE-2026-28770 Overview

CVE-2026-28770 is an XML Injection vulnerability affecting the International Datacasting Corporation (IDC) SFX Series SuperFlex Satellite Receiver Web management interface. The vulnerability exists in the /IDC_Logging/checkifdone.cgi script, which fails to properly sanitize user input from the file parameter before reflecting it into a CDATA block. This improper neutralization of special elements allows an authenticated attacker to break out of CDATA tags and inject arbitrary XML elements, potentially leading to reflected Cross-Site Scripting (XSS) attacks and possibly XML External Entity (XXE) exploitation.

Critical Impact

Authenticated attackers can inject arbitrary XML elements into the application response, enabling reflected XSS attacks against other users and potentially XXE-based attacks for data exfiltration or server-side request forgery.

Affected Products

• International Datacasting Corporation (IDC) SFX Series SuperFlex Satellite Receiver
• Web Management Interface version 101
• /IDC_Logging/checkifdone.cgi endpoint

Discovery Timeline

• 2026-03-04 - CVE-2026-28770 published to NVD
• 2026-03-05 - Last updated in NVD database

Technical Details for CVE-2026-28770

Vulnerability Analysis

This vulnerability stems from CWE-91: XML Injection (aka Blind XPath Injection), a weakness where the application fails to properly neutralize special elements used in XML parsing. The vulnerable endpoint /IDC_Logging/checkifdone.cgi accepts a file parameter and incorporates user-supplied values directly into an XML response structure, specifically within CDATA sections.

CDATA sections in XML are designed to contain character data that should not be parsed as markup. However, the application's failure to sanitize the file parameter allows attackers to inject the CDATA closing sequence (]]>) followed by arbitrary XML content. This effectively breaks out of the intended data context and enables injection of malicious XML elements.

The confirmed exploitation path involves crafting payloads that escape the CDATA block and inject script elements, resulting in reflected XSS. Additionally, the XML injection primitive may enable more severe attacks such as XXE (XML External Entity) injection, which could lead to file disclosure, server-side request forgery, or denial of service conditions.

Root Cause

The root cause of CVE-2026-28770 is insufficient input validation and output encoding in the /IDC_Logging/checkifdone.cgi script. The application directly incorporates user-supplied input from the file parameter into the XML response without sanitizing or escaping XML special characters such as ]]>, <, >, and &. This allows attackers to manipulate the XML document structure and inject malicious content that will be processed by the XML parser or rendered by the client browser.

Attack Vector

The attack requires network access to the web management interface and valid authentication credentials. An authenticated attacker can craft a malicious URL containing specially formatted XML injection payloads in the file parameter. When the vulnerable CGI script processes this request, the unsanitized input is reflected into the XML response, allowing the attacker to:

1. Break out of the CDATA section using the ]]> closing sequence
2. Inject arbitrary XML elements including script tags for XSS
3. Potentially define external entities for XXE attacks if the XML parser processes DTDs

The vulnerability is exploitable through direct requests to the affected endpoint. For reflected XSS scenarios, social engineering may be required to trick an authenticated administrator into clicking a malicious link.

Technical details and proof-of-concept information are available in the Abdulmhs Blog vulnerability analysis.

Detection Methods for CVE-2026-28770

Indicators of Compromise

• Unusual requests to /IDC_Logging/checkifdone.cgi containing XML special characters such as ]]>, <!ENTITY, or <script> tags in the file parameter
• Web server logs showing encoded payloads targeting the checkifdone.cgi endpoint with XML escape sequences
• Client-side JavaScript execution from the satellite receiver web interface domain that was not part of legitimate application functionality
• Network traffic containing malformed XML responses from the satellite receiver management interface

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block requests containing XML injection patterns such as ]]>, <!DOCTYPE, and <!ENTITY in URL parameters
• Configure intrusion detection systems (IDS) to alert on requests to /IDC_Logging/checkifdone.cgi with suspicious parameter values
• Enable verbose logging on the satellite receiver web interface and review for requests with encoded special characters
• Deploy endpoint detection and response (EDR) solutions to monitor for browser-based attacks originating from internal network segments

Monitoring Recommendations

• Monitor web server access logs for requests to the vulnerable checkifdone.cgi endpoint with abnormally long or encoded parameter values
• Implement network traffic analysis to detect XML injection attempt patterns targeting satellite receiver management interfaces
• Review authentication logs for the web management interface to identify potential credential compromise that could enable exploitation
• Establish baseline behavior for the satellite receiver management interface and alert on deviations

How to Mitigate CVE-2026-28770

Immediate Actions Required

• Restrict network access to the IDC SFX Series SuperFlex Satellite Receiver web management interface to trusted administrative networks only
• Implement firewall rules to block external access to port 80/443 on satellite receiver devices
• Review authentication credentials for the web management interface and ensure strong, unique passwords are in use
• Consider disabling the web management interface if not required for operational purposes

Patch Information

No vendor patch information is currently available for CVE-2026-28770. Consult the Abdulmhs Blog vulnerability analysis for the latest technical details and monitor International Datacasting Corporation communications for security updates.

Workarounds

• Isolate satellite receiver devices on a dedicated management VLAN with strict access controls limiting connectivity to authorized administrators only
• Deploy a reverse proxy or web application firewall in front of the management interface configured to sanitize XML special characters from input parameters
• Implement Content Security Policy (CSP) headers if possible through a reverse proxy to mitigate XSS impact
• Disable the web-based management interface and utilize alternative management methods such as serial console access where available
• Regularly audit access logs for the management interface to detect potential exploitation attempts

# Network isolation example using iptables
# Restrict access to satellite receiver web interface to management subnet only
iptables -A INPUT -p tcp --dport 80 -s 10.10.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 10.10.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP