CVE-2025-3929
📋 TL;DR
This is a cross-site scripting (XSS) vulnerability in MDaemon Email Server that allows attackers to execute arbitrary JavaScript in users' browsers via specially crafted HTML emails. The vulnerability affects webmail users of MDaemon version 25.0.1 and earlier, potentially exposing their email data and session information.
💻 Affected Systems
- MDaemon Email Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal user credentials, session cookies, and sensitive email data, potentially leading to account takeover and data exfiltration.
Likely Case
Attackers would steal session cookies to impersonate users, access their email accounts, and potentially use those accounts for phishing or further attacks.
If Mitigated
With proper email filtering and browser security controls, the impact would be limited to isolated user sessions without lateral movement.
🎯 Exploit Status
Exploitation requires sending malicious emails to target users who then view them in the webmail interface.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 25.0.2 or later
Vendor Advisory: https://mdaemon.com/pages/downloads-critical-updates
Restart Required: Yes
Instructions:
1. Download the latest version from MDaemon's critical updates page. 2. Run the installer to upgrade. 3. Restart the MDaemon service.
🔧 Temporary Workarounds
Disable HTML email rendering
windowsConfigure MDaemon to display emails as plain text only in webmail interface
Implement Content Security Policy
allAdd CSP headers to block inline JavaScript execution in webmail
🧯 If You Can't Patch
- Implement strict email filtering to block HTML emails with JavaScript
- Educate users to avoid opening suspicious emails in webmail interface
🔍 How to Verify
Check if Vulnerable:
Check MDaemon version in Admin console under Help > AboutCheck Version:
Not applicable - check via Admin console GUIVerify Fix Applied:
Verify version is 25.0.2 or later and test with safe XSS payload in test email📡 Detection & Monitoring
Log Indicators:
- Unusual email patterns with HTML/JavaScript content
- Multiple failed login attempts from new locations
Network Indicators:
- Emails with suspicious JavaScript in img tags
- Outbound connections to unknown domains from webmail server
SIEM Query:
source="mdaemon" AND ("javascript" OR "<img" OR "onerror")