KB5099540: Windows Server 2019 Security Update (July 2026)

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Download KB5099540

Get the official update for KB5099540. The download and file size for each supported product are on the Microsoft Update Catalog page.

Update summary

Senserva AI Opinion for KB5099540

KB5099540 is the July 2026 Security Update for Windows Server 2022 including Server Core, and it carries fixes for two zero-days flagged in the MSRC release: CVE-2026-56155 in AD FS, which is already exploited in the wild, and CVE-2026-50661 in BitLocker, which has been publicly disclosed. Any Server 2022 acting as an AD FS federation server is the priority exposure here, since attacks against that component are underway. Note the CVE detail is provisional because Microsoft has not yet published the per-update breakdown for this cycle.

Do this: Deploy KB5099540 to Windows Server 2022 hosts running AD FS first, then roll it out to the rest of your Server 2022 and Server Core estate.

AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for KB5099540

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

Full tracking and change history for KB5099540

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.

Exploitation and severity

Fixes 325 CVEs. At least one is actively exploited (CISA KEV). Most severe CVSS 9.9 (Critical). EPSS exploit probability up to 7.5%.

Among the top half of tracked Microsoft updates by EPSS exploit probability.

What to do

Treat as urgent: it is being exploited in the wild (CISA KEV), so patch ahead of items that are not. Senserva flags whether KB5099540 is missing on your devices.

Check if KB5099540 is installed

Copy-paste PowerShell: one machine, or your whole fleet in one pass. No output means the update is not installed.

Get-HotFix covers Windows updates. Office, SharePoint, and Exchange server updates show under installed updates in Programs and Features, or check the Update Catalog history.

Known issues, from Microsoft

Quoted from Microsoft's support article for KB5099540 (checked 2026-07-21). Verify against the article before acting.

Devices with an unrecommended BitLocker Group Policy configuration might be required to enter their BitLocker recovery key

Symptom

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 of 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 the article, Find your ...

Writing about KB5099540? Cite this page

Copy-paste for a blog post, forum answer, or internal doc. The link always carries the current risk data.

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.

What the press says about this update

Trusted-source coverage of the CVEs this update fixes, pulled live from their own feeds.

Affected products

• Windows 10 Version 1809 for 32-bit Systems
• Windows 10 Version 1809 for x64-based Systems
• Windows Server 2019

Also released in July 2026

The highest-risk updates from the same release:

The full month, summarized: Microsoft Patch Tuesday.

How to install KB5099540

Any of these paths delivers KB5099540; most organizations already have one of the first three running:

• Intune update rings (Windows Update for Business): the update flows on each ring's deferral schedule. For this update, consider an expedite policy: it bypasses deferrals for exactly this fix-now case.
• Windows Autopatch: rings, rollout, and pause or rollback are managed for you; exploited updates can be expedited.
• WSUS / Configuration Manager: approve KB5099540 for your device groups and set a deadline (deadline, not just approval, for an exploited fix).
• Manual: download from the Update Catalog above and install; fine for a handful of machines, unmanageable at any real scale.

After the rollout, verify rather than assume: update compliance reporting in Intune or Autopatch shows which devices actually installed it, and Siemserva reads Intune, Defender, Autopatch, and Azure Update Manager together to show the devices still missing KB5099540, ranked by exploitation.

Common questions about KB5099540

Does KB5099540 have known issues?

Yes. Microsoft's support article documents known issues for KB5099540 (checked 2026-07-21). The Known issues section on this page quotes it; verify against the article before acting.

Is KB5099540 urgent?

Yes. KB5099540 fixes at least one vulnerability in the CISA Known Exploited Vulnerabilities catalog, meaning attackers are using it in the wild. Deploy it first.

How do I download KB5099540?

From the Microsoft Update Catalog (linked on this page), or let Intune, Windows Update for Business, Windows Autopatch, or WSUS deliver it. The catalog page lists the download for each supported product.

How do I deploy KB5099540 with Intune?

Assign a Windows Update ring (quality update policy) to the device groups and the update flows on the ring's deferral schedule. Because KB5099540 fixes an actively exploited CVE, an Intune expedite policy is the right tool: it bypasses configured deferrals and pushes the update as soon as devices check in. Verify the rollout with update compliance reporting rather than assuming delivery.

Can I ask my own AI about KB5099540?

Yes. This page includes a free, ready-to-paste AI prompt containing KB5099540's key facts: severity, CVE count, exploitation status, and the download link. Copy it into Claude, ChatGPT, or Copilot for a rollout plan; the data is refreshed three times a day (5 AM, 12:30 PM, and 7 PM US Central).

Authoritative references