CVE-2021-47913
📋 TL;DR
PHP Melody 3.0 contains a persistent cross-site scripting vulnerability in the video editor's WYSIWYG component. Privileged users can inject malicious scripts that execute when other users view affected content, potentially leading to session hijacking and application manipulation. This affects PHP Melody 3.0 installations with users who have video editing privileges.
💻 Affected Systems
- PHP Melody
⚠️ Risk & Real-World Impact
Worst Case
Attackers with video editing privileges could inject scripts that hijack administrator sessions, steal credentials, deface the application, or redirect users to malicious sites.
Likely Case
Malicious privileged users inject scripts that execute when other users view videos, potentially stealing session cookies and performing actions as those users.
If Mitigated
With proper input validation and output encoding, scripts are neutralized before execution, preventing successful exploitation.
🎯 Exploit Status
Exploitation requires authenticated access with video editing privileges. The vulnerability is well-documented with proof-of-concept examples available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.0.1 or later
Vendor Advisory: https://www.phpsugar.com/phpmelody.html
Restart Required: No
Instructions:
1. Download PHP Melody 3.0.1 or later from the official website. 2. Backup your current installation. 3. Replace the vulnerable files with the patched version. 4. Clear any cached content. 5. Verify the fix by testing the video editor functionality.
🔧 Temporary Workarounds
Disable WYSIWYG Editor
allTemporarily disable the WYSIWYG editor in the video editing interface to prevent script injection.
Modify configuration to use plain text editor instead of WYSIWYG
Restrict Video Editing Privileges
allLimit video editing capabilities to only trusted administrators.
Review and modify user role permissions in PHP Melody admin panel
🧯 If You Can't Patch
- Implement strict input validation and output encoding for all user-controllable fields in the video editor
- Deploy a web application firewall (WAF) with XSS protection rules
🔍 How to Verify
Check if Vulnerable:
Test if the WYSIWYG editor in the video editing interface allows script tags to be saved and executed when viewing content.Check Version:
Check the PHP Melody version in the admin panel or configuration filesVerify Fix Applied:
Attempt to inject script tags via the video editor and verify they are properly sanitized or blocked.📡 Detection & Monitoring
Log Indicators:
- Unusual video editing activity from privileged accounts
- Script tags or JavaScript code in video descriptions or metadata
Network Indicators:
- Unexpected JavaScript execution in video content pages
- External script loading from video descriptions
SIEM Query:
Search for script tags or JavaScript patterns in video-related database entries or log files🔗 References
- https://www.phpsugar.com/blog/2021/09/php-melody-3-0-vulnerability-report-fix/
- https://www.phpsugar.com/phpmelody.html
- https://www.vulncheck.com/advisories/php-melody-persistent-cross-site-scripting-via-video-editor
- https://www.vulnerability-lab.com/get_content.php?id=2291
- https://www.vulnerability-lab.com/get_content.php?id=2291