CVE-2025-21230
📋 TL;DR
Microsoft Message Queuing (MSMQ) contains a vulnerability that allows attackers to cause a denial of service condition by sending specially crafted packets to affected systems. This affects Windows servers and workstations running MSMQ service. 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 requiring system restart to recover.
Likely Case
Temporary service disruption affecting message processing and application communication that relies on MSMQ.
If Mitigated
Minimal impact with proper network segmentation and monitoring in place to detect and block attack attempts.
🎯 Exploit Status
Attack requires network access to MSMQ service port (typically TCP 1801). No authentication needed to trigger the DoS condition.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Apply latest Windows security updates from Microsoft
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21230
Restart Required: Yes
Instructions:
1. Apply Windows security updates from Microsoft Update or WSUS. 2. Restart affected systems to complete installation. 3. Verify MSMQ service is functioning properly after restart.
🔧 Temporary Workarounds
Disable MSMQ Service
WindowsStop and disable MSMQ service if not required for business operations
Stop-Service -Name MSMQ
Set-Service -Name MSMQ -StartupType Disabled
Block MSMQ Ports
WindowsBlock network access to MSMQ ports using firewall rules
New-NetFirewallRule -DisplayName "Block MSMQ" -Direction Inbound -LocalPort 1801 -Protocol TCP -Action Block
🧯 If You Can't Patch
- Implement strict network segmentation to limit access to MSMQ services
- Deploy network monitoring and intrusion detection for MSMQ traffic patterns
🔍 How to Verify
Check if Vulnerable:
Check if MSMQ service is installed and running: Get-Service MSMQ | Select Status, StartTypeCheck Version:
Get-WmiObject -Class Win32_Service -Filter "Name='MSMQ'" | Select Name, State, StartModeVerify Fix Applied:
Verify Windows Update history for MSMQ-related patches and confirm MSMQ service version📡 Detection & Monitoring
Log Indicators:
- Event ID 5000 in Application log indicating MSMQ service failure
- High volume of connection attempts to port 1801
Network Indicators:
- Unusual traffic patterns to MSMQ port 1801
- Multiple connection resets or timeouts
SIEM Query:
source="windows" AND (event_id=5000 OR service="MSMQ") AND (status="stopped" OR error="access denied")