Microsoft Defender 'ShieldCrash' zero-day exploit grants SYSTEM access post-Patch Tuesday

An anonymous researcher released a Microsoft Defender zero-day exploit, 'ShieldCrash,' immediately after September 2026 Patch Tuesday, indicating a potential gap in Microsoft's patching. The exploit reportedly grants SYSTEM-level access, which if weaponized could enable full system compromise. Microsoft has not yet confirmed or patched the vulnerability, leaving Defender users exposed.