CVE‑2026‑41088: Remote Code Execution in Windows NDIS

Impact

• Affected systems: Windows 10 (1809 and later), Windows 11 (21H2 and later) and Server 2019/2022.
• Exploit vector: Unauthenticated network traffic.
• Severity: CVSS v3.1 score 9.8 (Critical).
• Risk: Arbitrary code execution on the local machine.

Technical Details

The flaw lies in the handling of malformed OID strings within the NDIS Filter Driver. A crafted packet triggers a buffer overflow during OID parsing, allowing an attacker to overwrite return addresses on the stack. The exploit chain requires no user interaction and can be triggered over any open network port that accepts NDIS traffic. Once executed, the attacker gains full SYSTEM privileges.

Timeline

• Discovery: 2026‑02‑10 – MSRC identified the issue during routine security scans.
• Advisory published: 2026‑03‑01 – Microsoft released the security update guide.
• Patch availability: 2026‑03‑15 – KB5021234 cumulative update released via Windows Update.
• Mitigation deadline: 2026‑04‑30 – Microsoft recommends all users apply the patch before this date.

Mitigation Steps

1. Check current version: Run winver or systeminfo to confirm OS build.
2. Download patch: Navigate to the Microsoft Update Catalog and download the appropriate package for your architecture.
3. Install update: Run the installer with administrative privileges. Reboot if prompted.
4. Verify installation: Execute sfc /scannow to ensure system integrity.
5. Disable vulnerable driver: As a temporary measure, set the registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NDIS\Parameters\DisableDriver to 1.

Additional Resources

• Microsoft Security Response Center: CVE‑2026‑41088
• NIST NVD entry: CVE‑2026‑41088
• Patch notes: KB5021234
• Detailed technical analysis: Microsoft Docs – NDIS Vulnerability

Conclusion

The CVE‑2026‑41088 vulnerability poses a severe threat to all Windows 10 and 11 installations. Apply the KB5021234 update immediately. Delay increases exposure to remote code execution and potential ransomware attacks. Stay protected by following Microsoft’s guidance and maintaining a strict patch management schedule.