CVE-2025-22888
📋 TL;DR
Movable Type's MT Block Editor has a stored XSS vulnerability in the custom block edit page. Attackers can inject malicious scripts that execute in logged-in users' browsers when they view affected pages. This affects all Movable Type installations using the vulnerable MT Block Editor component.
💻 Affected Systems
- Movable Type
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal administrator session cookies, perform actions as authenticated users, deface websites, or redirect users to malicious sites.
Likely Case
Attackers with editor access could inject scripts that execute when administrators view custom blocks, potentially stealing credentials or performing unauthorized actions.
If Mitigated
With proper input validation and output encoding, scripts would be rendered harmless as text rather than executable code.
🎯 Exploit Status
Exploitation requires authenticated access to edit custom blocks
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 8.4.2
Vendor Advisory: https://www.movabletype.org/news/2025/02/mt-842-released.html
Restart Required: Yes
Instructions:
1. Backup your Movable Type installation and database. 2. Download Movable Type 8.4.2 from the official website. 3. Replace existing files with the updated version. 4. Restart the web server. 5. Verify the update was successful.
🔧 Temporary Workarounds
Disable MT Block Editor
allTemporarily disable the vulnerable MT Block Editor component
Edit MT configuration to disable MT Block Editor feature
Restrict Custom Block Editing
allLimit who can edit custom blocks to trusted administrators only
Adjust user permissions in Movable Type admin panel
🧯 If You Can't Patch
- Implement strict Content Security Policy (CSP) headers to block inline scripts
- Use web application firewall (WAF) rules to detect and block XSS payloads
🔍 How to Verify
Check if Vulnerable:
Check Movable Type version in admin panel or via mt-check.cgiCheck Version:
Check Movable Type admin dashboard or view mt-config.cgiVerify Fix Applied:
Verify version is 8.4.2 or higher in admin dashboard📡 Detection & Monitoring
Log Indicators:
- Unusual custom block edits
- Suspicious script tags in content updates
- Multiple failed login attempts followed by block edits
Network Indicators:
- POST requests to custom block edit endpoints with script payloads
- Outbound connections to suspicious domains after viewing blocks
SIEM Query:
source="movabletype" AND (event="block_edit" OR event="content_update") AND (message="*script*" OR message="*javascript:*")