CVE-2025-61084
📋 TL;DR
MDaemon Mail Server 23.5.2 has an email spoofing vulnerability where attackers can use invisible Unicode thin spaces in the From: header to display a spoofed sender while passing SPF/DKIM/DMARC validation. This allows phishing emails to appear legitimate even with anti-spoofing protections enabled. Organizations using MDaemon Mail Server 23.5.2 are affected.
💻 Affected Systems
- MDaemon Mail Server
⚠️ 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
Successful phishing campaigns leading to credential theft, malware distribution, or business email compromise with emails appearing to come from trusted sources.
Likely Case
Targeted phishing attacks against employees or customers using spoofed sender addresses that bypass email authentication checks.
If Mitigated
Limited impact if Header Screening feature is properly configured or if email clients have their own spoofing protection.
🎯 Exploit Status
Exploitation requires sending crafted SMTP DATA with Unicode thin spaces in From: header. Public references available on GitHub.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: Not available
Restart Required: No
Instructions:
No official patch available. Vendor recommends using Header Screening feature or upgrading to latest version if available.
🔧 Temporary Workarounds
Enable Header Screening
windowsConfigure MDaemon's Header Screening feature to detect and block emails with suspicious Unicode characters in From: headers.
Configure via MDaemon Security -> Content Filter -> Header Screening
Upgrade to Latest Version
windowsCheck for and install any available updates beyond version 23.5.2 that may address this issue.
Check via MDaemon Help -> Check for Updates
🧯 If You Can't Patch
- Implement email gateway filtering for Unicode thin spaces in From: headers
- Enable additional email authentication checks and user awareness training
🔍 How to Verify
Check if Vulnerable:
Check MDaemon version via Help -> About. If version is 23.5.2, system is vulnerable.Check Version:
Not applicable - check via MDaemon GUIVerify Fix Applied:
Verify Header Screening is enabled and configured to block Unicode thin spaces in From: headers.📡 Detection & Monitoring
Log Indicators:
- SMTP logs showing emails with multiple Unicode characters in From: headers
- Header Screening rule violations
Network Indicators:
- SMTP traffic with crafted From: headers containing Unicode thin spaces
SIEM Query:
source="mdaemon" AND ("From:" AND "\u2009" OR "thin space")