These are the last few Windows 10 zero-day security updates you'll see without signing up to extended coverage

An illustration of an old PC with Windows 10's background on the screen.
(Image credit: Daniel Whittaker, Microsoft)
Recent updates

October 15, 2025: Changed the headline and some of the copy to note that the one-year extended security updates can be opted into for free if you are logged into a Microsoft account and have your settings synced. Previously the article stated that a $30 fee was required, but this has now been corrected.

If the past few weeks of being battered around the ears by calls to upgrade Windows 10 wasn't enough, the final cumulative update for the operating system might be a final reminder of why to do so. That's because the latest Windows 10 update, version KB5066791, fixes several zero-day vulnerabilities.

This might make you consider upgrading to Windows 11 because, well, this will be the very last time you'll be able to get a security update like this unless you get Extended Security Updates for a year (via Bleeping Computer). Thankfully this isn't too difficult, though, as if you're logged into your Microsoft account and syncing your settings, you can opt-in for free via your Windows Settings. This patch applies regardless, though.

The latest patch includes fixes for zero-day exploits including privilege escalation, secure boot bypass, memory corruption, and TPM information retrieval. 'Zero-day' means these exploits were discovered and exploitable before there was a fix released for them, meaning systems have been vulnerable to these ones until now.

Zero-days can be particularly scary, with devs scrambling to find a fix for them before users (or too many users) become affected by them. They're one of the main reasons to keep your system updated… provided you're offered those updates, of course, which is the whole point here.

As it stands, these important updates will install right away when Windows Update starts chugging, and then after the other smattering of updates in KB5066791 are done, that'll be it.

If you're considering upgrading to Windows 11 so you can keep receiving security (and other) updates, it might be best to do so using Rufus. The official Microsoft Media Creation Tool, which is usually used to create a Windows 11 installation drive, has recently stopped working for many Windows 10 users, but Rufus should still work.

Don't sweat it too much, either, if you're worried about upgrading. There are some differences between Windows 10 and 11, but they're hardly worlds apart, and most users should find the transition fine. You can also hang on for a little while longer to backup all your data properly before you upgrade, if that's your concern.

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Jacob Fox
Hardware Writer

Jacob got his hands on a gaming PC for the first time when he was about 12 years old. He swiftly realised the local PC repair store had ripped him off with his build and vowed never to let another soul build his rig again. With this vow, Jacob the hardware junkie was born. Since then, Jacob's led a double-life as part-hardware geek, part-philosophy nerd, first working as a Hardware Writer for PCGamesN in 2020, then working towards a PhD in Philosophy for a few years while freelancing on the side for sites such as TechRadar, Pocket-lint, and yours truly, PC Gamer. Eventually, he gave up the ruthless mercenary life to join the world's #1 PC Gaming site full-time. It's definitely not an ego thing, he assures us.

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