CVE-2021-47914
📋 TL;DR
PHP Melody 3.0 contains a persistent cross-site scripting vulnerability in the edit-video.php submitted parameter that allows remote attackers to inject malicious JavaScript. This can lead to session hijacking, phishing attacks, and manipulation of application modules. Anyone running PHP Melody 3.0 is affected.
💻 Affected Systems
- PHP Melody
⚠️ Risk & Real-World Impact
Worst Case
Attackers could hijack administrator sessions, take full control of the application, steal user credentials, and deploy persistent phishing pages to all visitors.
Likely Case
Attackers inject malicious scripts that steal user session cookies, redirect users to phishing sites, or deface the video platform.
If Mitigated
With proper input validation and output encoding, the malicious scripts would be neutralized and rendered harmless.
🎯 Exploit Status
Exploitation requires attacker access to edit video functionality; public proof-of-concept demonstrates the vulnerability.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version 3.0.1 or later
Vendor Advisory: https://www.phpsugar.com/blog/2021/09/php-melody-3-0-vulnerability-report-fix/
Restart Required: No
Instructions:
1. Download the latest version from the official PHP Melody website. 2. Backup your current installation. 3. Replace the vulnerable files with the patched version. 4. Verify the fix by testing the edit-video.php functionality.
🔧 Temporary Workarounds
Input Validation and Output Encoding
allImplement server-side validation and HTML encoding for the submitted parameter in edit-video.php
Edit edit-video.php to add htmlspecialchars() or similar encoding around user input
Content Security Policy
allImplement a strict Content Security Policy header to prevent script execution
Add header: Content-Security-Policy: default-src 'self'; script-src 'self'
🧯 If You Can't Patch
- Restrict access to edit-video.php functionality to trusted administrators only
- Implement web application firewall rules to block XSS payloads in the submitted parameter
🔍 How to Verify
Check if Vulnerable:
Test by submitting a script payload like <script>alert('XSS')</script> in the edit-video.php submitted parameter and check if it executesCheck Version:
Check the version number in the PHP Melody admin panel or configuration filesVerify Fix Applied:
After patching, test the same payload and verify it's properly encoded and doesn't execute📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to edit-video.php with script tags or JavaScript in parameters
- Multiple failed edit attempts with suspicious payloads
Network Indicators:
- HTTP requests containing <script> tags in the submitted parameter
- Unusual traffic patterns to edit-video.php
SIEM Query:
source="web_logs" AND uri="*edit-video.php*" AND (param="*<script>*" OR param="*javascript:*")