CVE-2025-21220
📋 TL;DR
Microsoft Message Queuing (MSMQ) contains an information disclosure vulnerability that allows authenticated attackers to read sensitive data from memory. This affects systems running vulnerable versions of Windows with MSMQ enabled. The vulnerability requires an attacker to have network access and valid credentials.
💻 Affected Systems
- Microsoft Windows
📦 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
Attackers could extract sensitive information like credentials, encryption keys, or application data from memory, potentially leading to further system compromise.
Likely Case
Unauthorized access to sensitive information stored in memory, potentially exposing application data or configuration details.
If Mitigated
Limited impact due to authentication requirements and network segmentation preventing unauthorized access.
🎯 Exploit Status
Requires authentication and network access to the MSMQ service. No public exploit code available at this time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Apply the latest Windows security updates from Microsoft's monthly Patch Tuesday releases
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21220
Restart Required: Yes
Instructions:
1. Apply Windows Update from Settings > Update & Security > Windows Update. 2. For enterprise environments, deploy through WSUS or Microsoft Endpoint Configuration Manager. 3. Restart affected systems after patch installation.
🔧 Temporary Workarounds
Disable MSMQ Service
WindowsIf MSMQ is not required, disable the service to eliminate the attack vector
sc config MSMQ start= disabled
sc stop MSMQ
Restrict Network Access
WindowsUse Windows Firewall to block inbound connections to MSMQ ports (TCP 1801, TCP 2103, TCP 2105, UDP 3527, UDP 1801)
netsh advfirewall firewall add rule name="Block MSMQ" dir=in action=block protocol=TCP localport=1801,2103,2105
netsh advfirewall firewall add rule name="Block MSMQ UDP" dir=in action=block protocol=UDP localport=3527,1801
🧯 If You Can't Patch
- Implement strict network segmentation to isolate MSMQ servers from untrusted networks
- Enforce strong authentication requirements and monitor for unusual access patterns to MSMQ services
🔍 How to Verify
Check if Vulnerable:
Check if MSMQ service is running: Get-Service 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 version matches patched release📡 Detection & Monitoring
Log Indicators:
- Unusual authentication attempts to MSMQ service
- Multiple failed connection attempts followed by successful authentication
- Unexpected process memory access events
Network Indicators:
- Unusual traffic patterns to MSMQ ports from unauthorized sources
- Multiple authentication requests from single source in short timeframe
SIEM Query:
source="windows" AND (event_id=4625 OR event_id=4648) AND process_name="mqsvc.exe"