CVE-2025-21290
📋 TL;DR
This vulnerability in Microsoft Message Queuing (MSMQ) allows attackers to cause a denial of service by sending specially crafted packets to vulnerable systems. It affects Windows servers and workstations running MSMQ services. The vulnerability could lead to service disruption or system instability.
💻 Affected Systems
- Microsoft Message Queuing (MSMQ)
📦 What is this software?
Windows 10 1507 by Microsoft
Windows 10 1507 by Microsoft
Windows 10 1607 by Microsoft
Windows 10 1607 by Microsoft
Windows 10 1809 by Microsoft
Windows 10 1809 by Microsoft
Windows 10 21h2 by Microsoft
Windows 10 22h2 by Microsoft
Windows 11 22h2 by Microsoft
Windows 11 23h2 by Microsoft
Windows 11 24h2 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Complete service outage of MSMQ functionality, potentially affecting dependent applications and causing business disruption.
Likely Case
MSMQ service becomes unresponsive or crashes, requiring service restart and causing temporary application connectivity issues.
If Mitigated
Minimal impact with proper network segmentation and monitoring; service may experience brief interruptions but can be quickly restored.
🎯 Exploit Status
Exploitation requires network access to MSMQ service port (typically TCP 1801). No authentication required to trigger the vulnerability.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Latest Windows security updates for affected versions
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21290
Restart Required: Yes
Instructions:
1. Apply latest Windows security updates from Microsoft Update Catalog or Windows Update. 2. Restart affected systems to complete installation. 3. Verify MSMQ service is running normally after restart.
🔧 Temporary Workarounds
Disable MSMQ Service
WindowsStop and disable MSMQ service if not required for business operations
sc stop MSMQ
sc config MSMQ start= disabled
Block MSMQ Ports
WindowsBlock network access to MSMQ ports using firewall rules
netsh advfirewall firewall add rule name="Block MSMQ" dir=in action=block protocol=TCP localport=1801
🧯 If You Can't Patch
- Implement strict network segmentation to isolate MSMQ servers from untrusted networks
- Deploy network monitoring and intrusion detection systems to detect DoS attempts against MSMQ services
🔍 How to Verify
Check if Vulnerable:
Check if MSMQ service is installed and running: Get-WindowsFeature MSMQ* (PowerShell) or sc query MSMQ (Command Prompt)Check Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify Windows Update history shows the latest security updates installed and MSMQ service is running without issues📡 Detection & Monitoring
Log Indicators:
- Event ID 7031 (Service terminated unexpectedly) for MSMQ service
- High volume of connection attempts to port 1801 in firewall logs
Network Indicators:
- Unusual traffic patterns to MSMQ port 1801
- Multiple connection attempts from single source IPs
SIEM Query:
source="windows" event_id=7031 AND service_name="MSMQ" OR destination_port=1801 AND protocol=TCP