CVE-2025-24011
📋 TL;DR
This vulnerability in Umbraco CMS allows attackers to determine whether specific user accounts exist by analyzing response codes and timing differences in management API responses. It affects Umbraco versions 14.0.0 through 14.3.1 and 15.0.0 through 15.1.1. This information disclosure could facilitate targeted attacks against valid user accounts.
💻 Affected Systems
- Umbraco CMS
📦 What is this software?
Umbraco Cms by Umbraco
Umbraco Cms by Umbraco
⚠️ Risk & Real-World Impact
Worst Case
Attackers could enumerate all valid user accounts, enabling targeted credential stuffing, brute force attacks, or social engineering against identified users.
Likely Case
Attackers identify valid administrative or user accounts, increasing the risk of successful account compromise through focused attacks.
If Mitigated
With proper patching, account enumeration is prevented, forcing attackers to guess valid usernames without confirmation.
🎯 Exploit Status
Exploitation involves analyzing HTTP response codes and timing differences, which can be automated with simple scripts.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 14.3.2 or 15.1.2
Vendor Advisory: https://github.com/umbraco/Umbraco-CMS/security/advisories/GHSA-hmg4-wwm5-p999
Restart Required: Yes
Instructions:
1. Backup your Umbraco installation and database. 2. Update to Umbraco version 14.3.2 (for v14) or 15.1.2 (for v15). 3. Restart the application. 4. Verify the update was successful.
🧯 If You Can't Patch
- Restrict network access to Umbraco management API endpoints using firewall rules or network segmentation.
- Implement rate limiting and monitoring for suspicious API access patterns.
🔍 How to Verify
Check if Vulnerable:
Check Umbraco version via the admin dashboard or by examining the Umbraco assembly version. If version is between 14.0.0-14.3.1 or 15.0.0-15.1.1, the system is vulnerable.Check Version:
Check the Umbraco version in the admin interface at /umbraco or examine the Umbraco.Core.dll assembly version.Verify Fix Applied:
Confirm Umbraco version is 14.3.2 or higher (for v14) or 15.1.2 or higher (for v15). Test API endpoints to ensure consistent response times and codes regardless of account existence.📡 Detection & Monitoring
Log Indicators:
- Multiple failed authentication attempts with different usernames against management API endpoints
- Unusual patterns of API requests with timing analysis characteristics
Network Indicators:
- High volume of requests to Umbraco management API with varying usernames
- Requests followed by analysis of response timing
SIEM Query:
source="umbraco" AND (uri_path="/umbraco/api/*" OR uri_path="/api/umbraco/*") AND (status_code=401 OR status_code=404) | stats count by src_ip, username