Patch tracker / KB5087420
KB5087420: Windows Server 2019 Security Update (May 2026)
Updated July 21, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.
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Microsoft security update released 2026-05-12. Fixes 56 CVEs.
All about KB5087420: the download, the Senserva AI read, a PowerShell installed-check, install guidance, the CVEs it fixes, and its change history.
KB5087420 is a Critical security update for Windows Server 2019, released 2026-05-12. It closes 56 CVEs with a maximum CVSS of 9.8. Get it from the Microsoft Update Catalog below, and see where it sits against the rest of the month on the patch tracker.
No exploitation is confirmed for the CVEs in this update and the EPSS exploitation probability is currently 2.4%. That can change: CVEs from past updates regularly get exploited months later, which is why deploying on your normal cadence, without exceptions that linger, is what keeps this one boring.
Most organizations deliver an update like this automatically through Intune update rings, Windows Update for Business, Windows Autopatch, or WSUS; the install section below covers each path. For the bigger picture: how the Microsoft patching tools fit together, this month's Patch Tuesday summary, and every update ranked by real-world risk.
Download KB5087420
Get the official update for KB5087420. The download and file size for each supported product are on the Microsoft Update Catalog page.
Update summary
Senserva AI Opinion for KB5087420
KB5087420 is a large rollup for Windows 10 Version 1809 and Windows Server 2019 that closes 56 CVEs, with the worst rated Critical at CVSS 9.8, meaning unauthenticated remote code execution is plausible. Nothing here is in the CISA KEV catalog or tied to ransomware, and the highest EPSS is only 2 percent, so there is no confirmed exploitation yet. The exposure matters because 1809 and Server 2019 are common in longer-lived infrastructure where patching lags.
Do this: Deploy KB5087420 to your Windows 10 1809 and Server 2019 hosts this cycle, prioritizing any internet-facing Server 2019 systems that could be hit by the CVSS 9.8 remote code execution flaw.
AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for KB5087420
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for KB5087420
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 56 CVEs. Most severe CVSS 9.8 (Critical). EPSS exploit probability up to 2.4%.
Among the lower half of tracked Microsoft updates by EPSS exploit probability.
What to do
Elevated priority: high severity or a meaningful exploitation probability, sooner if an affected product is internet-facing. Senserva flags whether KB5087420 is missing on your devices.
Check if KB5087420 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.
Writing about KB5087420? 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.
| CVE | Severity | CVSS | EPSS | Exploited |
|---|---|---|---|---|
| CVE-2025-54518 | Critical | 9.8 | 72% | No |
| CVE-2026-21530 | Critical | 9.8 | 72% | No |
| CVE-2026-32161 | Critical | 9.8 | 72% | No |
| CVE-2026-32170 | Critical | 9.8 | 72% | No |
| CVE-2026-32209 | Critical | 9.8 | 72% | No |
| CVE-2026-33834 | Critical | 9.8 | 72% | No |
| CVE-2026-33835 | Critical | 9.8 | 72% | No |
| CVE-2026-33837 | Critical | 9.8 | 72% | No |
| CVE-2026-33838 | Critical | 9.8 | 72% | No |
| CVE-2026-33839 | Critical | 9.8 | 72% | No |
| CVE-2026-33841 | Critical | 9.8 | 72% | No |
| CVE-2026-34329 | Critical | 9.8 | 72% | No |
| CVE-2026-34330 | Critical | 9.8 | 72% | No |
| CVE-2026-34331 | Critical | 9.8 | 72% | No |
| CVE-2026-34333 | Critical | 9.8 | 72% | No |
| CVE-2026-34334 | Critical | 9.8 | 72% | No |
| CVE-2026-34336 | Critical | 9.8 | 72% | No |
| CVE-2026-34337 | Critical | 9.8 | 72% | No |
| CVE-2026-34338 | Critical | 9.8 | 72% | No |
| CVE-2026-34339 | Critical | 9.8 | 72% | No |
| CVE-2026-34340 | Critical | 9.8 | 72% | No |
| CVE-2026-34341 | Critical | 9.8 | 72% | No |
| CVE-2026-34342 | Critical | 9.8 | 72% | No |
| CVE-2026-34343 | Critical | 9.8 | 72% | No |
| CVE-2026-34344 | Critical | 9.8 | 72% | No |
| CVE-2026-34345 | Critical | 9.8 | 72% | No |
| CVE-2026-34347 | Critical | 9.8 | 72% | No |
| CVE-2026-34351 | Critical | 9.8 | 72% | No |
| CVE-2026-35415 | Critical | 9.8 | 72% | No |
| CVE-2026-35416 | Critical | 9.8 | 72% | No |
| CVE-2026-35417 | Critical | 9.8 | 72% | No |
| CVE-2026-35418 | Critical | 9.8 | 72% | No |
| CVE-2026-35421 | Critical | 9.8 | 72% | No |
| CVE-2026-35422 | Critical | 9.8 | 72% | No |
| CVE-2026-35423 | Critical | 9.8 | 72% | No |
| CVE-2026-35424 | Critical | 9.8 | 72% | No |
| CVE-2026-40377 | Critical | 9.8 | 72% | No |
| CVE-2026-40380 | Critical | 9.8 | 72% | No |
| CVE-2026-40382 | Critical | 9.8 | 72% | No |
| CVE-2026-40397 | Critical | 9.8 | 72% | No |
| CVE-2026-40398 | Critical | 9.8 | 72% | No |
| CVE-2026-40399 | Critical | 9.8 | 72% | No |
| CVE-2026-40401 | Critical | 9.8 | 72% | No |
| CVE-2026-40402 | Critical | 9.8 | 72% | No |
| CVE-2026-40403 | Critical | 9.8 | 72% | No |
| CVE-2026-40406 | Critical | 9.8 | 72% | No |
| CVE-2026-40407 | Critical | 9.8 | 72% | No |
| CVE-2026-40408 | Critical | 9.8 | 72% | No |
| CVE-2026-40410 | Critical | 9.8 | 72% | No |
| CVE-2026-40413 | Critical | 9.8 | 72% | No |
| CVE-2026-40414 | Critical | 9.8 | 72% | No |
| CVE-2026-40415 | Critical | 9.8 | 72% | No |
| CVE-2026-41088 | Critical | 9.8 | 72% | No |
| CVE-2026-41096 | Critical | 9.8 | 72% | No |
| CVE-2026-41097 | Critical | 9.8 | 72% | No |
| CVE-2026-42825 | Critical | 9.8 | 72% | No |
Affected products
Also released in May 2026
The highest-risk updates from the same release:
The full month, summarized: Microsoft Patch Tuesday.
How to install KB5087420
Any of these paths delivers KB5087420; 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.
- Windows Autopatch: rings, rollout, and pause or rollback are managed for you; exploited updates can be expedited.
- WSUS / Configuration Manager: approve KB5087420 for your device groups and set a deadline.
- 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 KB5087420, ranked by exploitation.
Common questions about KB5087420
Is KB5087420 urgent?
KB5087420 is rated Critical with a maximum CVSS of 9.8. No active exploitation is confirmed yet, so schedule it in your prompt patch cycle.
How do I download KB5087420?
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 KB5087420 with Intune?
Assign a Windows Update ring (quality update policy) to the device groups and the update flows on the ring's deferral schedule. For urgent updates, Intune expedite policies can bypass the ring deferrals. Verify the rollout with update compliance reporting rather than assuming delivery.
Can I ask my own AI about KB5087420?
Yes. This page includes a free, ready-to-paste AI prompt containing KB5087420'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
See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.
