Patch tracker / KB5099538
KB5099538: Windows Server 2019 Security Update (July 2026)
KB5099538 is a Critical security update for Windows Server 2019, released 2026-07-14. It closes 308 CVEs with a maximum CVSS of 9.9. At least one of them is actively exploited (CISA KEV), so it is urgent, and Microsoft lists 1 known issue: test it before broad deployment. The most likely of them to be attacked is CVE-2026-32202, which FIRST.org rates at 71% probability of exploitation in the next 30 days.
Before you deploy: Microsoft lists 1 known issue for this update.
Our data comes from Microsoft, CISA and other public sources, and it can be wrong or out of date. If you are unsure, check the linked source before you act, and tell us when we are wrong so we can fix it.
Update summary
Fixes 308 CVEs. At least one is actively exploited (CISA KEV). Most severe CVSS 9.9 (Critical). EPSS exploit probability up to 71%. 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: KB5126651 (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 1 known issue with this update.
- We are currently not aware of any issues with this update.
KB5099538 is an unusually large rollup for Windows 10 1809 and Windows Server 2019, fixing 311 CVEs in a single release with a top Severity of Critical at CVSS 9.9. One of these vulnerabilities is already on the CISA Known Exploited Vulnerabilities list, so at least one flaw is confirmed exploited in the wild even though none are currently tied to ransomware. The peak EPSS of 11 percent is modest, but the KEV listing plus the 9.9 score is what makes this batch a priority for 1809 and Server 2019 fleets still in support.
Do this: Deploy KB5099538 to all Windows 10 1809 and Windows Server 2019 systems now, prioritizing internet-facing servers because of the 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 KB5099538
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for KB5099538
- Released
- 2026-07-14
- Last changed
- 2026-10-28
- Changes tracked
- 10
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 KB5099538 on 2026-10-28: CVEs fixed 312 to 308.
- 2026-07-29 CVEs fixed 311 to 312
- 2026-10-13 CVEs fixed 312 to 313
- 2026-10-25 CVEs fixed 313 to 312
- 2026-10-28 CVEs fixed 312 to 308
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 KB5099538 is installed
Elevated PowerShell. No output means it is not installed.
Known issues, from Microsoft
Quoted from Microsoft's support article for KB5099538 (checked 2026-11-03). Microsoft lists 1 known issue. Verify against the article before acting.
We are currently not aware of any issues with this update.
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
182 CVEs · Critical · exploitedKB5099445
171 CVEs · Critical · exploitedKB5099535
258 CVEs · Critical · exploitedKB5099536
383 CVEs · Critical · exploitedKB5099539
310 CVEs · Critical · exploitedKB5099540
322 CVEs · Critical · exploitedKB5101649
377 CVEs · Critical · exploitedKB5101650
374 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.