Patch tracker / KB5099540
KB5099540: Windows Server 2019 Security Update (July 2026)
KB5099540 is a Critical security update for Windows Server 2019, released 2026-07-14. It closes 326 CVEs with a maximum CVSS of 9.9. At least one of them is actively exploited (CISA KEV), so this is a deploy-first update. The most likely of them to be attacked is CVE-2026-42982, which FIRST.org rates at 64% probability of exploitation in the next 30 days.
Update summary
Fixes 326 CVEs. At least one is actively exploited (CISA KEV). Most severe CVSS 9.9 (Critical). EPSS exploit probability up to 64%. Among the top 25% of tracked Microsoft updates by EPSS exploit probability.
A newer security update for Windows 10 Version 1809 for 32-bit Systems has shipped since this one: KB5094041 (2026-08-11). 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 2 known issues with this update.
- Devices with an unrecommended BitLocker Group Policy configuration might be required to enter their BitLocker recovery key
- Windows Server Update Services (WSUS) does not display error details
KB5099540 is a large July 2026 rollup for Windows 10 version 1809 and Windows Server 2019 that fixes 325 CVEs, with the worst rated Critical at CVSS 9.9 and at least one CVE already listed in the CISA Known Exploited Vulnerabilities catalog. The confirmed exploitation matters more than the modest 11% top EPSS here, since KEV listing means attacks are observed in the wild rather than merely predicted. Server 2019 domain controllers and any remaining 1809 endpoints are the exposed population.
Do this: Deploy KB5099540 to your Windows Server 2019 and 1809 systems now, prioritizing internet-facing and domain controller hosts because of the CISA KEV listed CVE.
AI-generated from public data, 2026-07-25. 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
- Released
- 2026-07-14
- Last changed
- 2026-07-29
- Changes tracked
- 3
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.
Microsoft revised KB5099540 on 2026-07-29: CVEs fixed 325 to 326.
- 2026-07-29 CVEs fixed 325 to 326
Recorded by Senserva on the dates shown, from the MSRC release feed. This is what moved and when, which neither the vendor advisory nor NVD publishes.
Check if KB5099540 is installed
Elevated PowerShell. No output means it is not installed.
Known issues, from Microsoft
Quoted from Microsoft's support article for KB5099540 (checked 2026-08-11). 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 ...
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
- Also released in July 2026
KB5099444
185 CVEs · Critical · exploitedKB5099445
174 CVEs · Critical · exploitedKB5099535
261 CVEs · Critical · exploitedKB5099536
389 CVEs · Critical · exploitedKB5099538
312 CVEs · Critical · exploitedKB5099539
314 CVEs · Critical · exploitedKB5101649
383 CVEs · Critical · exploitedKB5101650
380 CVEs · Critical · exploitedThe full month, summarized: Microsoft Patch Tuesday.
- Authoritative references
See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.