CVE-2025-22389
📋 TL;DR
This vulnerability in Optimizely EPiServer CMS Core allows attackers to upload malicious files like .docm and .html due to improper file validation. When users access these files, they can execute malicious actions or compromise systems. All systems running affected versions are vulnerable.
💻 Affected Systems
- Optimizely EPiServer CMS Core
📦 What is this software?
Optimizely Cms by Optimizely
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, and lateral movement within the network.
Likely Case
Malware distribution to users through malicious documents, credential theft via phishing pages, or limited server-side file execution.
If Mitigated
Uploaded malicious files remain inert without user interaction, but still pose storage and potential access risks.
🎯 Exploit Status
Requires attacker to have upload permissions and victim to access the malicious file. No public exploit code available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 12.32.0 or later
Vendor Advisory: https://support.optimizely.com/hc/en-us/articles/33182404079629-Content-Management-System-CMS-Security-Advisory-CMS-2025-03
Restart Required: No
Instructions:
1. Backup your CMS installation and database. 2. Upgrade to EPiServer.CMS.Core version 12.32.0 or later. 3. Test functionality after upgrade. 4. Monitor for any issues.
🔧 Temporary Workarounds
File Upload Restriction
allImplement server-side file type validation to block .docm, .html, and other dangerous extensions.
Implement custom file validation in upload handlers to reject dangerous file types
Content Security Policy
allDeploy CSP headers to prevent execution of uploaded HTML files in browser context.
Add Content-Security-Policy header to restrict script execution from untrusted sources
🧯 If You Can't Patch
- Implement strict file upload validation at web server level (IIS/Apache/Nginx)
- Isolate file upload directory with execute permissions disabled
🔍 How to Verify
Check if Vulnerable:
Check installed EPiServer.CMS.Core version via package manager or assembly version.Check Version:
Check EPiServer.CMS.Core.dll file version or use NuGet package managerVerify Fix Applied:
Confirm version is 12.32.0 or later and test file upload with malicious extensions is blocked.📡 Detection & Monitoring
Log Indicators:
- File uploads with .docm, .html extensions
- Unusual file upload patterns
- Access to uploaded files with suspicious extensions
Network Indicators:
- HTTP POST requests to upload endpoints with dangerous file types
- Downloads of uploaded files with suspicious extensions
SIEM Query:
source="web_server" (method="POST" uri="*upload*" AND (file_extension=".docm" OR file_extension=".html"))