CVE-2026-4847: muucmf CMS XSS Vulnerability

CVE-2026-4847 Overview

A Cross-Site Scripting (XSS) vulnerability has been identified in dameng100 muucmf version 1.9.5.20260309. The vulnerability exists in an unknown function of the file /admin/config/list.html, where improper handling of the Name argument allows attackers to inject malicious scripts. This flaw enables remote attackers to execute arbitrary JavaScript code in the context of a victim's browser session. The exploit has been publicly disclosed, and the vendor was contacted but did not respond to responsible disclosure attempts.

Critical Impact

Remote attackers can inject malicious scripts through the Name parameter in the admin configuration interface, potentially leading to session hijacking, credential theft, or unauthorized administrative actions within the muucmf content management framework.

Affected Products

• dameng100 muucmf version 1.9.5.20260309

Discovery Timeline

• 2026-03-26 - CVE CVE-2026-4847 published to NVD
• 2026-03-26 - Last updated in NVD database

Technical Details for CVE-2026-4847

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 affected component is the administrative configuration interface at /admin/config/list.html within the muucmf content management framework. When processing the Name argument, the application fails to properly sanitize user-supplied input before rendering it in the HTML response. This allows an attacker to craft malicious input containing JavaScript code that will be executed in the browser of any user viewing the affected page.

The attack requires network access and some form of user interaction, as the victim must navigate to or interact with a page containing the injected payload. Given that the vulnerable endpoint is in the administrative interface, successful exploitation could allow attackers to perform actions with elevated privileges or steal administrator session tokens.

Root Cause

The root cause of this vulnerability is insufficient input validation and output encoding in the muucmf administrative configuration module. When the Name parameter is submitted to /admin/config/list.html, the application does not properly sanitize or escape special HTML characters before including them in the page output. This lack of proper output encoding allows script tags and JavaScript event handlers to be interpreted as executable code rather than plain text.

Attack Vector

The vulnerability is exploitable over the network without requiring authentication to initiate the attack, though user interaction is required for the malicious script to execute. An attacker can craft a specially designed request to the /admin/config/list.html endpoint with a malicious Name parameter value containing JavaScript code. When an administrator or user views the affected configuration page, the injected script executes within their browser session.

The attack scenario typically involves:

1. The attacker crafts a malicious URL or form submission containing XSS payload in the Name parameter
2. A victim with access to the admin panel interacts with the malicious content
3. The victim's browser executes the attacker's JavaScript code
4. The attacker can steal session cookies, perform actions as the victim, or redirect to phishing pages

For detailed technical analysis of this XSS vulnerability, refer to the GitHub XSS Configuration Post which contains the public disclosure information.

Detection Methods for CVE-2026-4847

Indicators of Compromise

• Unusual or suspicious values in the Name parameter of requests to /admin/config/list.html
• Configuration entries containing HTML script tags, event handlers, or encoded JavaScript
• Unexpected outbound connections from administrator browsers to unknown domains
• Modified configuration entries with suspicious content containing <script>, onerror, onload, or similar HTML event attributes

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block XSS payloads in HTTP requests targeting /admin/config/list.html
• Enable detailed logging for all administrative interface access and monitor for unusual parameter values
• Deploy browser security headers such as Content-Security-Policy (CSP) to mitigate the impact of successful XSS attacks
• Use endpoint detection solutions to identify suspicious JavaScript execution patterns in administrator sessions

Monitoring Recommendations

• Monitor HTTP request logs for the /admin/config/list.html endpoint, particularly examining the Name parameter for script injection attempts
• Set up alerts for configuration changes that contain HTML tags or JavaScript code
• Review access logs for unusual patterns of administrative interface access
• Implement integrity monitoring for stored configuration values to detect unauthorized modifications

How to Mitigate CVE-2026-4847

Immediate Actions Required

• Restrict access to the administrative interface (/admin/config/list.html) to trusted IP addresses only
• Implement additional authentication layers for administrative functions
• Deploy a Web Application Firewall with XSS protection rules in front of the muucmf application
• Audit existing configuration entries for any signs of injected malicious content

Patch Information

No official patch has been released by the vendor. According to the vulnerability disclosure, the vendor (dameng100) was contacted about this issue but did not respond. Organizations using muucmf should consider implementing compensating controls or evaluating alternative solutions.

For additional vulnerability details, refer to VulDB #353152.

Workarounds

• Implement strict input validation on the Name parameter to allow only alphanumeric characters and safe symbols
• Apply output encoding (HTML entity encoding) to all user-supplied data rendered in the administrative interface
• Configure Content-Security-Policy headers to prevent inline script execution
• Consider using a reverse proxy with XSS filtering capabilities to inspect and sanitize requests before they reach the application

# Example Apache configuration to restrict admin access by IP
<Location /admin/>
    Require ip 192.168.1.0/24
    Require ip 10.0.0.0/8
</Location>

# Example nginx configuration
location /admin/ {
    allow 192.168.1.0/24;
    allow 10.0.0.0/8;
    deny all;
}