CVE-2025-34398
📋 TL;DR
MailEnable versions before 10.54 contain a reflected XSS vulnerability in the AddressesBcc parameter of the AddressBook.aspx page. Attackers can craft malicious URLs that execute JavaScript in victims' browsers when they attempt to send emails, potentially stealing session cookies or redirecting users. This affects all MailEnable users running vulnerable versions.
💻 Affected Systems
- MailEnable
📦 What is this software?
Mailenable by Mailenable
⚠️ Risk & Real-World Impact
Worst Case
Attackers steal authenticated session cookies, hijack email accounts, redirect users to phishing sites, and perform actions as the authenticated user including sending malicious emails from the victim's account.
Likely Case
Attackers steal non-HttpOnly session cookies to hijack authenticated sessions, potentially accessing email accounts and sensitive information.
If Mitigated
With proper input validation and output encoding, the malicious payload would be neutralized, preventing script execution.
🎯 Exploit Status
Exploitation requires the victim to be authenticated and to click a malicious link while using the webmail interface. The attack vector is well-documented and relatively simple to execute.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 10.54
Vendor Advisory: https://mailenable.com/Standard-ReleaseNotes.txt
Restart Required: Yes
Instructions:
1. Download MailEnable version 10.54 or later from the official website. 2. Run the installer to upgrade your existing installation. 3. Restart the MailEnable services. 4. Verify the update was successful by checking the version in the administration console.
🔧 Temporary Workarounds
Input Validation Filter
allImplement web application firewall rules or input validation to sanitize the AddressesBcc parameter
WAF rule: Block requests containing script tags or JavaScript syntax in AddressesBcc parameter
Disable Webmail Access
windowsTemporarily disable webmail access if not required, forcing users to use desktop email clients
IIS: Disable the /Mondo/ virtual directory
Windows Firewall: Block port 80/443 for webmail
🧯 If You Can't Patch
- Implement strict Content Security Policy headers to prevent inline script execution
- Deploy a web application firewall with XSS protection rules specifically for the AddressesBcc parameter
🔍 How to Verify
Check if Vulnerable:
Test by accessing the vulnerable page with a test payload in the AddressesBcc parameter and checking if it executesCheck Version:
Check MailEnable version in Administration Console or via registry: HKEY_LOCAL_MACHINE\SOFTWARE\MailEnableVerify Fix Applied:
After patching, attempt the same test payload and verify it does not execute and is properly sanitized📡 Detection & Monitoring
Log Indicators:
- Unusual GET requests to /Mondo/lang/sys/Forms/AddressBook.aspx with script-like content in parameters
- Multiple failed login attempts followed by successful login from same IP
Network Indicators:
- HTTP requests containing JavaScript syntax in the AddressesBcc parameter
- Unusual redirects from the webmail interface
SIEM Query:
source="mailenable.log" AND uri="/Mondo/lang/sys/Forms/AddressBook.aspx" AND (param="AddressesBcc" AND value CONTAINS "script" OR "javascript:" OR "<" OR ">")