Patch tracker / KB5002578
KB5002578: Windows Server 2019 Security Update (May 2026)
KB5002578 is a Medium security update for Windows Server 2019, released 2026-05-12. It closes 1 CVE with a maximum CVSS of 6.7. The most likely of them to be attacked is CVE-2026-21530, which FIRST.org rates at 80% probability of exploitation in the next 30 days.
Update summary
Fixes 1 CVE. Most severe CVSS 6.7 (Medium). EPSS exploit probability up to <1%. Among the lower half 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: KB5089548 (2026-07-14). 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.
We checked Microsoft's support article for KB5002578 on 2026-08-07 and it lists no known issues. Read the article before broad deployment; Microsoft adds issues as reports come in, and we re-check on every refresh.
KB5002578 patches a single flaw, CVE-2026-21530, affecting Windows 10 version 1809 (32-bit and x64) and Windows Server 2019. Its Medium severity at CVSS 6.7 with a 0 percent EPSS and no presence in the CISA KEV catalog means active exploitation is not currently indicated. The narrow scope makes this a routine hygiene update rather than an emergency for most environments.
Do this: Schedule KB5002578 in your next standard patch cycle for any remaining Windows 10 1809 or Server 2019 hosts.
AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for KB5002578
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for KB5002578
- Released
- 2026-05-12
- Last changed
- 2026-05-12
- Changes tracked
- 1
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.
Check if KB5002578 is installed
Elevated PowerShell. No output means it is not installed.
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-2026-21530 | Critical | 9.8 | 80% | No |
Scope and sources
- Affected products
- Also released in May 2026
KB5002863
9 CVEs · High · exploitedKB5002868
9 CVEs · High · exploitedKB5002870
9 CVEs · High · exploitedKB5078943
3 CVEs · CriticalKB5087420
56 CVEs · CriticalKB5087424
56 CVEs · CriticalKB5087470
39 CVEs · CriticalKB5087471
42 CVEs · CriticalThe full month, summarized: Microsoft Patch Tuesday.
- Authoritative references
See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.