Microsoft has released the Windows 10 KB5099539 cumulative update as part of the July 2026 Patch Tuesday rollout. The update upgrades Windows 10 version 22H2 to Build 19045.7548 and Windows 10 Enterprise LTSC 2021 to Build 19044.7548.
KB5099539 addresses 570 security vulnerabilities, including two actively exploited zero-day flaws and one publicly disclosed zero-day vulnerability. It also improves Remote Desktop security, strengthens networking protections, expands the Secure Boot certificate rollout, and fixes several reliability and compatibility issues.
Because Windows 10 reached end of support in October 2025, KB5099539 is available only for eligible devices enrolled in Microsoft’s Extended Security Updates (ESU) program and supported Windows 10 Enterprise LTSC editions.
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What’s New in Windows 10 KB5099539?
The July 2026 Windows 10 update focuses on security, reliability, and compatibility improvements rather than introducing new features. Here are the most important changes included in KB5099539:
- Fixes compatibility issues affecting some legacy and business applications.
- Restores the OneDrive shortcut in File Explorer when running with administrator privileges.
- Fixes the Recycle Bin confirmation dialog to display the correct file name.
- Improves keyboard shortcut reliability for certain built-in Windows experiences.
- Expands the Secure Boot certificate rollout and adds dynamic status reporting in Windows Security.
- Strengthens networking security by enforcing TDI transport registration requirements.
- Enhances Remote Desktop (RDP) security with SHA-2 certificate thumbprint support.
- Addresses 570 security vulnerabilities, including two actively exploited zero-day flaws and one publicly disclosed zero-day vulnerability.
Reliability and Compatibility Improvements
KB5099539 resolves several reliability issues introduced by previous Windows updates. Microsoft fixed a compatibility issue in OLE Automation (oleaut32.dll) that affected some legacy and business applications. The update also restores the OneDrive shortcut in File Explorer when it’s launched with administrator privileges.
In addition, Microsoft also fixed an issue where the Recycle Bin confirmation dialog displayed an internal file name instead of the original file name. The update also improves keyboard hotkey handling to enhance system stability. If certain keyboard shortcuts stop responding after installation, restarting the affected application usually resolves the issue.
Security Enhancements
The July 2026 update also strengthens Windows 10 security in several areas. Microsoft continues expanding the rollout of updated Secure Boot certificates by adding dynamic status reporting in the Windows Security app and deploying new certificates to more eligible devices.
The update also strengthens networking security by enforcing Transport Driver Interface (TDI) registration requirements. In addition, it improves Remote Desktop (RDP) security by adding support for SHA-2 certificate thumbprints for trusted publishers.
July 2026 Security Updates
Alongside quality improvements, KB5099539 includes Microsoft’s latest July 2026 Patch Tuesday security updates, addressing 570 vulnerabilities across Windows and other Microsoft products. The release includes two actively exploited zero-day vulnerabilities and one publicly disclosed zero-day vulnerability, making it one of the most important Windows 10 security updates this year.
Among the most notable fixes are:
- CVE-2026-56155 – An Elevation of Privilege vulnerability in Active Directory Federation Services (AD FS) that was actively exploited.
- CVE-2026-56164 – An Elevation of Privilege vulnerability affecting Microsoft SharePoint Server, which was also actively exploited.
- CVE-2026-50661 – A Windows BitLocker Security Feature Bypass vulnerability that was publicly disclosed and could allow unauthorized access to encrypted data if an attacker has physical access to the device.
Microsoft recommends installing KB5099539 as soon as it’s available to receive the latest security protections and improve the stability of supported Windows 10 devices.
Known Issues
At the time of release, Microsoft had not reported any major new issues specifically introduced by KB5099539. However, due to changes in keyboard hotkey cleanup behavior, some built-in Windows experiences may temporarily stop responding to certain keyboard shortcuts. In most cases, restarting the affected application resolves the issue.
Should You Install Windows 10 KB5099539?
Yes. If your Windows 10 PC is enrolled in the Extended Security Updates (ESU) program or you’re running a supported Windows 10 Enterprise LTSC edition, installing KB5099539 is recommended. In addition to fixing several known issues, the update addresses 570 security vulnerabilities, including two actively exploited zero-day flaws, helping protect your PC against the latest security threats.
How to Install Windows 10 KB5099539
Microsoft is rolling out KB5099539 automatically through Windows Update for eligible Windows 10 devices.
To install the update:
- Open Settings by pressing Windows + I
- Go to Update & Security, then Windows Update.
- Now, click the Check for updates button, and you will see the 2026-07 Cumulative Update for Windows 10 Version 22H2 (KB5099539)) has started downloading.
- Once done, restart your PC to apply the updates.
Alternatively, you can download the offline installer from the Microsoft Update Catalog and install the update manually.
- Visit the Microsoft Update Catalog.
- Search for “KB5099539” and select the appropriate version (e.g., 32-bit, 64-bit, or ARM64) based on your system.
- Download the .msu file, double-click it to run the installer, and follow the prompts. Restart your device to complete the process.
If you are looking for the Windows 10 version 22H2 ISO image, you can download it from here.
Windows 10 KB5099539 update Direct Download Links: 64-bit and 32-bit (x86).
The link above opens the Microsoft Update Catalog, a public library of previously released Windows Updates. You can click on the ‘Download’ button next to the version of Windows you’ve installed and begin the download by clicking on .msu link, which appears in the next pop-up.
Because Windows 10 is now supported only through the ESU program, Microsoft recommends upgrading to Windows 11 to continue receiving feature updates, security patches, and long-term support.
Frequently Asked Questions
KB5099539 is the July 2026 cumulative security update for eligible Windows 10 devices enrolled in Microsoft’s Extended Security Updates (ESU) program and supported Windows 10 Enterprise LTSC editions. It upgrades Windows 10 version 22H2 to Build 19045.7548 and Enterprise LTSC 2021 to Build 19044.7548.
No. KB5099539 does not introduce any major new features. Instead, it focuses on security updates, reliability improvements, Secure Boot enhancements, Remote Desktop security, networking protections, and fixes for several known issues.
Yes. Microsoft recommends installing KB5099539 because it addresses 570 security vulnerabilities, including two actively exploited zero-day vulnerabilities and one publicly disclosed zero-day vulnerability, while also improving system reliability and security.
The update is available through Windows Update for eligible devices. You can also download the standalone installer from the Microsoft Update Catalog if you prefer to install it manually.
Yes, but only for eligible devices enrolled in Microsoft’s Extended Security Updates (ESU) program and supported Windows 10 Enterprise LTSC editions. Standard consumer editions of Windows 10 reached end of support in October 2025.
Source: Microsoft Support – July 14, 2026—KB5099539 (OS Builds 19045.7548 and 19044.7548)
