CVE-2024-55488
📋 TL;DR
A stored cross-site scripting (XSS) vulnerability in Umbraco CMS v14.3.1 allows authenticated attackers with CMS access to inject malicious scripts that execute when other users view affected content. This affects organizations using Umbraco CMS v14.3.1 where authenticated users have content editing privileges. The vendor disputes this as a vulnerability since it requires authenticated access and represents a deliberate design choice.
💻 Affected Systems
- Umbraco CMS
📦 What is this software?
Umbraco Cms by Umbraco
⚠️ Risk & Real-World Impact
Worst Case
Authenticated malicious users could steal session cookies, perform account takeover, deface websites, or redirect users to malicious sites through persistent XSS payloads.
Likely Case
Privilege escalation within the CMS, session hijacking of other authenticated users, or content manipulation by users with editing permissions.
If Mitigated
Limited impact with proper access controls and user privilege management, as exploitation requires authenticated CMS access.
🎯 Exploit Status
Exploitation requires authenticated access to Umbraco CMS. Technical details and proof-of-concept are publicly available in NCC Group advisory.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: None
Vendor Advisory: http://umbraco.com
Restart Required: No
Instructions:
No official patch available as vendor disputes this as a vulnerability. Consider implementing workarounds or upgrading to future versions if vendor changes position.
🔧 Temporary Workarounds
Implement Content Security Policy (CSP)
allAdd Content-Security-Policy headers to restrict script execution sources
Add to web.config or server headers: Content-Security-Policy: default-src 'self'; script-src 'self'
Implement Input Validation/Sanitization
allAdd custom sanitization for rich text editor inputs before storage
Implement HTML sanitization library (like DOMPurify) in custom code handling rich text input
🧯 If You Can't Patch
- Implement strict access controls and least privilege principles for CMS users
- Regularly audit user activities and content changes in Umbraco CMS
🔍 How to Verify
Check if Vulnerable:
Check Umbraco version in admin panel or web.config file for version 14.3.1Check Version:
Check Umbraco admin dashboard or examine web.config for version informationVerify Fix Applied:
Verify no official fix exists; verify workarounds are implemented by testing CSP headers and input sanitization📡 Detection & Monitoring
Log Indicators:
- Unusual content updates in Umbraco audit logs
- Multiple failed login attempts followed by content modifications
Network Indicators:
- HTTP requests containing suspicious script tags in POST data to Umbraco endpoints
SIEM Query:
source="umbraco" AND (event="content_update" AND (data CONTAINS "<script>" OR data CONTAINS "javascript:"))