Patch tracker / KB5094127
KB5094127: Windows 10 Version 21H2 Security Update (June 2026)
KB5094127 is a Critical security update for Windows 10 Version 21H2, released 2026-06-09. It closes 148 CVEs with a maximum CVSS of 9.8. It is the second largest of the 30 updates Microsoft shipped that month, by CVEs closed.
Update summary
Fixes 148 CVEs. Most severe CVSS 9.8 (Critical). EPSS exploit probability up to 2.3%. Among the top half of tracked Microsoft updates by EPSS exploit probability.
A newer security update for Windows 10 Version 21H2 for ARM64-based Systems has shipped since this one: KB5126657 (2026-10-13). For cumulative update families the newer package includes these fixes, so installing that one is usually the shorter path. Verify against your own update rings before you skip this package.
Microsoft documents 4 known issues with this update.
- Devices with an unrecommended BitLocker Group Policy configuration might be required to enter their BitLocker recovery key
- Microsoft Office applications might fail to open from certain third-party apps
- Deleting from Recycle Bin displays an internal file name
KB5094127 is a large June 2026 rollup for Windows 10 1809 and Windows Server 2019 that closes 148 CVEs, topped by a Critical issue rated CVSS 9.8. One flaw carries a 54% EPSS score, meaning exploitation in the wild is more probable than not even though none of these CVEs are in CISA KEV or tied to ransomware yet. The combination of a large CVE count and a near-coin-flip exploit likelihood on the worst bug makes this a priority for any remaining 1809 and Server 2019 fleets.
Do this: Deploy KB5094127 to all Windows 10 1809 and Windows Server 2019 systems this cycle, prioritizing internet-facing Server 2019 hosts first.
AI-generated from public data, 2026-07-26. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for KB5094127
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for KB5094127
- Released
- 2026-06-09
- Last changed
- 2026-10-05
- Changes tracked
- 5
Senserva began recording day-to-day change history on 2026-07-07, and refreshes it several times a day. Release dates are historical where Microsoft publishes them; revision history is tracked from that date forward, so it does not include changes made before then.
Check if KB5094127 is installed
Elevated PowerShell. No output means it is not installed.
Known issues, from Microsoft
Quoted from Microsoft's support article for KB5094127 (checked 2026-10-03). Verify against the article before acting.
Devices with an unrecommended BitLocker Group Policy configuration might be required to enter their BitLocker recovery key
Symptoms
Some devices with an unrecommended BitLocker Group Policy configuration might be required to enter their BitLocker recovery key on the first restart after installing this update.
This issue only affects a limited number of systems in which ALL the following conditions are true. These conditions are unlikely to be found on personal devices not managed by IT departments.
BitLocker is enabled on the OS drive.
The Group Policy Configure TPM platform validation profile for native UEFI firmware configurations is configured, and PCR7 is included in the validation profile (or the equivalent registry key is set manually).
System Information (msinfo32.exe) reports Secure Boot State PCR7 Binding as Not Possible .
The Windows UEFI CA 2023 certificate is present in the device’s Secure Boot Signature Database (DB), making the device eligible for the 2023‑signed Windows Boot Manager to be made the default.
The device is not already running the 2023-signed Windows Boot Manager.
In this scenario, the BitLocker recovery key only needs to be entered once -- subsequent restarts will not trigger a BitLocker recovery screen, as long as the group policy configuration remains unchanged. For help finding your BitLocker recovery key, see [Find your BitLocker recovery key](https://support.microsoft.com/Windows/Security/Encryption/find-your-bitlocker-recovery-key).
Enterprises are recommended to audit their BitLocker group policies for explicit PCR7 inclusion and check msinfo32.exe for their PCR7 binding status before installing this update.
Resolution
This issue is addressed in update KB5122878 . After installing update KB5122878, devices with this incompatible group policy configuration are prevented from installing the 2023-signed Windows Boot Manager. If your device was impacted, Event ID 1032 will appear in the System event log when installing Windows updates: "The Secure Boot update Boot Manager (2023) was not applied due to a known incompatibility with the current BitLocker configuration."
If you receive Event ID 1032 , Microsoft strongly recommends removing the Group Policy configuration before installing updates so that you can install the 2023-signed Windows Boot Manager and continue to receive the latest Secure Boot protection.
Remove the Group Policy configuration before installing the update (Recommended)
Open Group Policy Editor (gpedit.msc) or your Group Policy Management Console.
Navigate to: Computer Configuration > Administrative ...
CVEs fixed by this update
Sorted exploited-first, then by CVSS. Every CVE links to its Senserva page with the full risk facts, references, and a ready-to-paste AI prompt.
Scope and sources
- Affected products
- Windows 10 Version 21H2 for 32-bit Systems
- Windows 10 Version 21H2 for ARM64-based Systems
- Windows 10 Version 21H2 for x64-based Systems
- Windows 10 Version 22H2 for 32-bit Systems
- Windows 10 Version 22H2 for ARM64-based Systems
- Windows 10 Version 22H2 for x64-based Systems
- Windows Server, version 2004 (Server Core installation)
- Also released in June 2026
KB5002873
31 CVEs · Critical · exploitedKB5002874
31 CVEs · Critical · exploitedKB5002880
30 CVEs · Critical · exploitedKB5093998
158 CVEs · CriticalKB5094041
67 CVEs · CriticalKB5094042
64 CVEs · CriticalKB5094122
76 CVEs · CriticalKB5094123
89 CVEs · CriticalThe full month, summarized: Microsoft Patch Tuesday.
- Authoritative references
See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.