New Microsoft Defender Update Lands for Windows ISO Images

Microsoft has released a new Microsoft Defender update package for Windows installation images, refreshing the security protection included with Windows setup media following the August 2026 Patch Tuesday updates.

The package targets WIM, VHD, and ISO installation images and helps prevent freshly installed Windows systems from starting with outdated Defender components and malware definitions.

Microsoft Defender package gets new security intelligence

The latest package brings Microsoft Defender security intelligence version 1.455.50.0 to supported Windows installation images.

Microsoft updated the core Defender components to the following versions:

• Platform version: 4.18.26070.9
• Engine version: 1.1.26070.7
• Security intelligence version: 1.455.50.0
• Defender package version: 1.455.50.0

Microsoft periodically refreshes its Defender installation-image packages because Windows installation media can remain unchanged for long periods. Without these updates, a newly installed system could initially use older Defender binaries and malware definitions until Windows Update downloads newer protection.

Windows 11, Windows 10, and Server versions are supported

The new Defender package applies to several Windows client and server releases, including:

• Windows 11
• Windows 10 (ESU, Enterprise LTSC 2021, Enterprise LTSC 2019, Enterprise LTSB 2016)
• Windows Server (2022, 2019, 2016)

The package updates the protection built directly into supported Windows installation media rather than replacing the regular Defender update mechanism after installation.

Live Defender definitions are already newer

Although the installation-image package contains security intelligence version 1.455.50.0, Microsoft’s regular Defender security intelligence has already reached version 1.457.181.0 at the time of writing.

As a result, systems installed from updated media can still receive newer malware definitions through standard Microsoft Defender updates once Windows connects to the internet.

Microsoft has also released Recovery Updates KB5120999 and KB5121002 following the August updates.

Separately, Microsoft recently patched the LegacyHive Windows zero-day as part of its latest security fixes.

Via Neowin