Microsoft releases new Defender update for Windows 11, 10, Server ISO installations

When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. Microsoft released a new Defender update for Windows 10 and 11 ISO images. According to the company, this update should be deployed across all new Windows 11 and 10 installs.

 

Sayan Sen Neowin · Mar 8, 2026 04:12 EDT

Microsoft releases new Windows Defender update packages very frequently to protect against various newly discovered malware. Once a while every three months or so, the company also pushes out these updates to Windows images (WIM and VHD) and ISOs, that are used to install Windows.

This update package is necessary as a Windows installation image may contain old, outdated anti-malware definitions and software binaries. Aside from better security, these updates can also provide improved performance benefits in some cases.

When a new Windows installation is set up, there may be a temporary security risk due to outdated Microsoft Defender protection in the OS installation images. This happens because the antimalware software included in these images might not be up to date. Thus Microsoft says that these updated definitions essentially help close this protection gap.

Microsoft delivered the latest security definitions for Windows images via security intelligence update version 1.445.6.0. The Defender package version is also the same. It applies to Windows 11, Windows 10 ESU, Windows 10 Enterprise LTSC 2021, Win 10 Ent LTSC 2019, Win 10 Ent LTSB 2016, Windows Server 2022, Windows Server 2019, and Windows Server 2016.

Microsoft writes: "This package updates the anti-malware client, anti-malware engine, and signature versions in the OS installation images to the following versions:

Platform version: 4.18.26010.5 Engine version: 1.1.26010.1 Security intelligence version: 1.445.6.0"

From Microsoft's security bulletin, we learn that the security intelligence update version 1.445.6.0 was released early last month and adds threat detections for various malware like trojan, backdoor exploits, AutoKMS, and more.

For those wondering, the latest intelligence update is version 1.445.415.0 at the time of writing.

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