Microsoft has pushed out the Windows 10 KB5099539 extended security update, bundling fixes from the record-breaking July 2026 Patch Tuesday along with additional security improvements specific to the Extended Security Update program.
The July Patch Tuesday alone addressed 570 flaws, including three zero-days — two of which were already being exploited in active attacks. The KB5099539 update ensures that Windows 10 devices on ESU plans get these same critical fixes.
If you’re running Windows 10 on an ESU subscription, this update is essential. The breadth of vulnerabilities patched this month makes it one of the largest security update cycles Microsoft has ever shipped. Delaying installation leaves a significant attack surface exposed.
Administrators should prioritize testing and deployment. The three zero-days represent active threats, and the sheer volume of fixes means there are likely more vulnerabilities that attackers could reverse-engineer from the patches.
References
- Bleeping Computer: Microsoft releases Windows 10 KB5099539 extended security update
- Microsoft Security Response Center
This article was originally reported by Bleeping Computer. Rewritten and published by The Coolest Info.
