IRONSMITHINTEL
CRITICAL
|Auth: varies by cve|Reboot: required|Est. 30–60 minutes including reboot|Manual only

KB5055526: Windows Server 2022 Cumulative Update (May 2026)

The April 2026 Patch Tuesday update for Windows Server 2022 includes fixes for multiple security vulnerabilities including privilege escalation and remote code execution.

Published May 3, 2026 · Updated May 10, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

Depending on which CVEs are included, attackers can exploit unpatched servers for remote code execution, privilege escalation, or credential theft. Servers that miss monthly cumulative updates accumulate multiple unpatched vulnerabilities simultaneously.

How the attack works

Microsoft's April 2026 Patch Tuesday includes the monthly cumulative update for Windows Server 2022. This update bundles all previously released security fixes plus new patches for vulnerabilities discovered since the March 2026 update. Like all cumulative updates, it must be applied as a complete package — individual fixes cannot be installed separately.

Am I affected?Quick check

Probably yes if any of these apply:

●All Windows Server 2022 systems
●Running Windows Server 2022 prior to KB5055526

Affected OS versions

Windows Server 2022
Fixed inKB5055526
Real-world incidentsWhat we've seen

An organisation that applies patches 30 days late on average has a predictable window of vulnerability. During April 2026, servers missing this update are exposed to all vulnerabilities patched this month. Ransomware operators specifically target organisations known for delayed patching.

How to patch

Manual download

For air-gapped servers or out-of-band deployment. Microsoft Update Catalog returns every OS-version variant of this update.

↗ Microsoft Update CatalogKB5055526

Manual remediation steps

⏱ 30–60 minutes including reboot

Check if KB5055526 is Installed

Get-HotFix -Id KB5055526
# If no output, the patch is not installed

Apply via Windows Update

1
Open Settings → Windows Update
2
Click Check for updates
3
Install all available updates
4
Restart when prompted

Apply Manually (for servers without internet access)

1
Download KB5055526 from Microsoft Update Catalog: catalog.update.microsoft.com
2
Run the MSU installer
3
Restart the server

Apply via WSUS / SCCM

Approve KB5055526 in your patch management console and deploy to Windows Server 2022 systems.

Verification

Get-HotFix -Id KB5055526
# Must show the KB with an InstalledOn date

# Also verify Windows version
[System.Environment]::OSVersion.Version
PowerShell automationComing soon

No tested PowerShell script for this entry yet. We’re prioritising automation based on user demand.

References

↗ MSRC Advisory↗ KBKB5055526