New Windows SignDrop flaw can give attackers SYSTEM access
Nov 12, 2026 · Summarized by Fundy Tech from BleepingComputer
A researcher says a Windows zero-day called SignDrop can be used to gain SYSTEM privileges. He says Microsoft's CLFS mitigation introduced the flaw and a patch is still needed.
Key points
- Abdelhamid Naceri disclosed the SignDrop exploit.
- It targets Microsoft's CLFS mitigation added in October 2025.
- Naceri says about 80% of Windows installations may be vulnerable.
Why it matters
If you run Windows on a home or business device, a successful attack could give malware deep control of the system. That can defeat security tools and make cleanup harder. For now, the practical step is to check whether a device is vulnerable and wait for a Microsoft patch.
Who’s affected: Windows devices using CLFS mitigation
What to do
- Check whether your Windows device is vulnerable.
- Run the proof-of-concept only on systems you own.
- Watch for a Microsoft patch.
Original reporting
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