Over the weekend, security researcher Abdelhamid Naceri (also known as Nightmare Eclipse) released another Microsoft Defender zero-day exploit that blocks antivirus updates.

Microsoft has resolved a known issue that causes incorrect alerts warning that Defender Antivirus was turned off after installing recent updates.

The most important is CVE-2026-96951, a security feature bypass flaw in Windows that has been exploited in the wild.

Recently, Microsoft delivered its latest Defender patches for Windows 11 ISOs. These definitions are released from time to time alongside the general security updates available during Patch Tuesday.

Want to know how to enable Windows Defender in Windows 11? In this easy step-by-step tutorial, I’ll show you how to turn on Windows Defender Antivirus and check your Windows Security settings to help ...

This voice experience is generated by AI. Learn more. This voice experience is generated by AI. Learn more. New warnings are a mistake. Microsoft has now confirmed that new warnings alarming Windows ...

A patch Microsoft released on Wednesday to fix a zero-day vulnerability in its Defender security engine may cause Windows machines to write files large enough to completely consume available disk ...

Microsoft Defender expands to Linux desktops in public preview, bringing antivirus, threat detection, vulnerability management, and response tools.

BigDiskBuster can block Microsoft Defender updates by filling disk space, leaving detection content stale; no patch or advisory exists.

The majority of the updates that come through Windows Update are for Windows Defender, and for good reason. Windows Defender helps make your antimalware and other security protections stronger.