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New Microsoft Defender 'ShieldCrash' zero-day grants SYSTEM access
September 9, 2026 · BleepingComputer · Severity: CRITICAL
An anonymous security researcher known as Nightmare Eclipse has released a new Microsoft Defender zero-day exploit called ShieldCrash that bypasses Windows Defender protections and grants system-level access. The exploit targets the Microsoft Defender Antivirus service and demonstrates a method to disable real-time protection. Microsoft has been notified and is investigating.
Key Takeaways
- Active exploitation detected — patch immediately to prevent compromise
- Affected systems should be identified and prioritized for remediation
- Monitor for additional indicators of compromise as investigations evolve