CVE-2026-4847

Summary

A medium-severity Cross-Site Scripting vulnerability (CVE-2026-4847) has been identified in dameng100 muucmf 1.9.5.20260309. The application renders user-supplied input into web pages without proper output encoding, allowing attackers to inject malicious scripts (CWE-79).

Technical Details

The issue is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation) with secondary classification under CWE-94 (Code Injection). The affected component accepts user input through HTTP parameters and reflects it directly into the HTML response without applying context-appropriate encoding.

This creates a reflected XSS vector where an attacker crafts a malicious URL containing JavaScript payloads. When a victim clicks the link, the injected script executes in their browser session.

Exploitation Context

• Vector: Remote / Network-based
• Authentication: Not required
• Complexity: Low
• Impact: Medium (Confidentiality and Integrity)

XSS attacks can escalate significantly depending on the application context — session cookie theft leads to account takeover, and keyloggers injected via XSS can capture credentials entered on the compromised page.

Remediation

Developers and administrators should immediately:

1. Apply context-appropriate output encoding at every point where user input is rendered into HTML (use htmlspecialchars() in PHP with ENT_QUOTES flag).
2. Implement Content Security Policy (CSP) headers to restrict script execution sources and mitigate the impact of any residual XSS.
3. Deploy input validation with strict whitelists for expected data formats.

Precogs AI Integration

The Precogs AI Code Security Platform detects XSS by performing inter-procedural taint analysis from HTTP input sources to HTML rendering sinks. Precogs verifies that context-appropriate output encoding is applied at every injection point, covering reflected, stored, and DOM-based XSS patterns across PHP, JavaScript, Python, and Java applications.

Vulnerability Code Signature

Attack Data Flow

Vulnerable Code Pattern

// ❌ VULNERABLE: Direct DOM injection
const userComment = urlParams.get('comment');
// Taint sink: innerHTML executes injected scripts
document.getElementById('comments').innerHTML = userComment;

Secure Code Pattern

// ✅ SECURE: Safe DOM manipulation
const userComment = urlParams.get('comment');
// Sanitized binding: textContent escapes HTML entities
document.getElementById('comments').textContent = userComment;

How Precogs Detects This

Precogs AI Analysis Engine maps untrusted input sources directly to sensitive DOM manipulation functions, detecting Cross-Site Scripting (XSS) paths before deployment.\n