Microsoft releases Windows 10 KB5120249 extended security update

Summary

Microsoft has issued the Windows 10 KB5120249 Extended Security Update (ESU) for versions 22H2 and 21H2, addressing security vulnerabilities and bugs. This mandatory update includes the August 2026 Patch Tuesday security fixes, resolving issues such as File History backup failures and expanding Secure Boot certificate deployment. Microsoft reports no known new issues with this release.

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Microsoft releases Windows 10 KB5120249 extended security update By Mayank Parmar August 11, 2026 02:26 PM 0 Microsoft has released the Windows 10 KB5120249 Extended Security Updates (ESU) for versions 22H2 and 21H2 to fix security vulnerabilities and bugs. Today's update is mandatory as it contains the August 2026 Patch Tuesday security updates. You can install today's update by going to Start > Settings > Update & Security > Windows Update and clicking on 'Check for updates.' You can also manually download and install the update from the Microsoft Update Catalog. After installing today's update, Windows 10 will be updated to OS Builds 19045.7663 and 19044.7663. What's new in the Windows 10 August 2026 Patch Tuesday update With today's update, Microsoft is fixing a File History backup issue and expanding the rollout of new Secure Boot certificates. Here's the full list of improvements and fixes: [Backup] File History automatic backups to network shares using Server Message Block (SMB) might fail with an incorrect "invalid credentials" error. When this issue occurs, scheduled backups do not copy any files. This update resolves the issue. [Secure Boot] This update includes additional high confidence device targeting data, increasing coverage of devices eligible to automatically receive new Secure Boot certificates. Microsoft also said that Secure Boot certificate deployment via Windows updates continues across supported PCs and non-managed business devices in the coming months. Microsoft is not aware of any new issues with this month's Patch Tuesday update, but we'll update the article if we come across major problems. Once attackers have valid credentials, only 37% of their actions are blocked Overall prevention scores can hide what happens after initial access. Once attackers are using valid credentials, prevention drops sharply.The Blue Report 2026 measures defenses technique by technique across 338 million simulations run in customer production environments. Get the report Related Articles: Microsoft fixes Recycle Bin prompts broken by June Windows updatesNew Windows RasMan zero-day flaw gets free, unofficial patchesWindows 11 24H2 Home and Pro reach end of support in 90 daysMicrosoft releases Windows 10 KB5099539 extended security updateMicrosoft: Windows Backup now available for enterprise users

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