CVE-2025-47981
📋 TL;DR
A heap-based buffer overflow vulnerability in Windows SPNEGO Extended Negotiation allows unauthenticated attackers to execute arbitrary code remotely over a network. This affects Windows systems using SPNEGO for authentication negotiation. The high CVSS score indicates critical severity requiring immediate attention.
💻 Affected Systems
- 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
Complete system compromise with remote code execution leading to full administrative control, data exfiltration, and lateral movement across the network.
Likely Case
Remote code execution with SYSTEM privileges, enabling malware deployment, credential theft, and persistent backdoor installation.
If Mitigated
Attack blocked at network perimeter with proper segmentation and endpoint protection; limited to isolated systems if exploited internally.
🎯 Exploit Status
The description indicates unauthorized network-based exploitation, suggesting relatively straightforward attack vectors once details are known.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Microsoft Security Update Guide for specific patch versions
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-47981
Restart Required: Yes
Instructions:
1. Visit Microsoft Security Update Guide for CVE-2025-47981
2. Download and apply the appropriate security update for your Windows version
3. Restart the system as required
🔧 Temporary Workarounds
Block SPNEGO Extended Negotiation
windowsDisable or restrict SPNEGO Extended Negotiation features to prevent exploitation
Check Microsoft advisory for specific registry or policy settings
🧯 If You Can't Patch
- Implement strict network segmentation to isolate vulnerable systems from untrusted networks
- Deploy intrusion detection/prevention systems to monitor for SPNEGO exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check Windows Update history for applied patches related to CVE-2025-47981 or use Microsoft's security update verification toolsCheck Version:
wmic os get caption,version,buildnumberVerify Fix Applied:
Verify the security update is installed via Windows Update or system patch management tools📡 Detection & Monitoring
Log Indicators:
- Unusual SPNEGO negotiation failures
- Unexpected process creations from network services
- Security log entries indicating buffer overflow attempts
Network Indicators:
- Anomalous SPNEGO traffic patterns
- Unexpected network connections to authentication services
SIEM Query:
Search for events related to SPNEGO authentication failures or unusual service behavior on Windows systems🔗 References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-47981
- https://www.vicarius.io/vsociety/posts/cve-2025-47981-detection-script-heap-based-buffer-overflow-in-windows-spnego-extended-negotiation
- https://www.vicarius.io/vsociety/posts/cve-2025-47981-mitigation-script-heap-based-buffer-overflow-in-windows-spnego-extended-negotiation
