Microsoft promptly patched this week's 'wormable' Windows 10 flaw

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Just days after details leaked about a vulnerability, Microsoft sent out a fix.

Surface Laptop 3 15
Surface Laptop 3 15 (Image credit: Future)

What you need to know

  • New cumulative updates are available for Windows 10 1909 and 1903.
  • The updates address the wormable vulnerability that was recently discussed in online leaks.
  • The bug didn't affect any versions of Windows 10 older than 1903.

Microsoft shipped out cumulative updates for Windows 10 version 1909 and Windows 10 version 1903 today. The updates address a vulnerability in the Microsoft Server Message Block 3.1.1 (SMBv3). The updates come just days after Microsoft's March Patch Tuesday updates.

The fix addresses a wormable vulnerability that we reported on earlier this week. Details of the vulnerability leaked online ahead of Patch Tuesday, and a fix for it was not included in the Patch Tuesday updates. Now, Microsoft has addressed the issue. Here's the highlight, as listed by a Microsoft support page:

  • Security update to the Microsoft Server Message Block 3.1.1 (SMBv3).

If you check the changelog from the support page, it lists the update to SMVv3 below Windows 10 version 1903 and not Windows 10 version 1909. That's because the two versions share a common core operating system and identical system files. Any changes listed in version 1903 are also available for version 1909.

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Sean Endicott
Sean Endicott
News Writer

Sean Endicott is a News Writer at Windows Central, where he covers Windows 11, Surface hardware, Microsoft 365, AI, apps, and the broader PC ecosystem. Since joining the site in 2017, he has written well over a thousand articles across the Microsoft landscape, covering breaking news, analysis, and feature reporting.

He writes Windows Wrap, a weekly column covering the biggest stories in Windows and the PC industry, and what they mean for the platform going forward.

Before joining Windows Central full-time, Sean worked in journalism and media production after earning a First Class degree in Broadcast Journalism from Nottingham Trent University. Outside of tech, he is an award-winning American football coach based in Nottingham, England, and was named BAFCA Youth Coach of the Year in 2024.