Microsoft has released a crucial Extended Security Update (ESU) for Windows 10, addressing critical vulnerabilities and bugs that could leave systems exposed to attacks. The update, marked as KB5120249, is mandatory for all affected versions of Windows 10 – specifically 22H2 and 21H2 – and includes the August 2026 Patch Tuesday security updates.
To install this update, users can head to their Settings menu, click on “Update & Security,” and then select “Windows Update.” Alternatively, they can manually download the update from the Microsoft Update Catalog. Following installation, Windows 10 will be updated to OS Builds 19045.7663 and 19044.7663.
The KB5120249 ESU brings several key improvements and fixes to the table. One notable issue it resolves is related to File History backups, which would often fail with an “invalid credentials” error when using Server Message Block (SMB) protocol on network shares. Scheduled backups will now function correctly without any issues.
Another significant aspect of this update is its expansion of Secure Boot certificate deployment. This feature ensures that Windows systems can only boot from trusted firmware and hardware, reducing the risk of malware infections during startup. By incorporating additional high-confidence device targeting data, Microsoft aims to increase the coverage of devices eligible for automatic receipt of new Secure Boot certificates.
It’s worth noting that once attackers gain valid credentials, prevention rates plummet. According to a recent report, only 37% of attacker actions are blocked after they’ve gained access with legitimate credentials. This highlights the importance of timely and comprehensive security updates like the one provided by Microsoft in KB5120249.
For organizations and individuals relying on Windows 10, it’s essential to prioritize installing this update as soon as possible. Not doing so may leave your system vulnerable to potential attacks. In practical terms, users should take a few minutes to ensure their systems are up-to-date with the latest security patches. This simple step can significantly reduce the risk of falling prey to common cyber threats.
In summary, the KB5120249 ESU is a critical update for Windows 10 users, addressing pressing vulnerabilities and improving system security. By installing this update, you’ll be taking a significant step towards protecting your device from potential attacks.
Source: Bleeping Computer — 2026-08-11