BigDiskBuster Exploit Freezes Microsoft Defender Updates on All Windows Versions
Security researcher Abdelhamid Naceri, known as Nightmare Eclipse, released a new proof-of-concept exploit called BigDiskBuster that prevents Microsoft Defender from installing platform and signature updates. The tool, published on September 19, 2026, works by filling available disk space to block update downloads on all supported Windows versions. While Defender remains active, its detection capabilities become stale. Microsoft has not issued a patch or CVE for this specific flaw, though it has addressed several other zero-days disclosed by Naceri in recent months. The exploit is part of an ongoing dispute between Naceri and Microsoft over his termination.