Patch tracker / KB5078737
KB5078737: Windows Server 2019 Security Update (May 2026)
KB5078737 is a High security update for Windows Server 2019, released 2026-05-12. It closes 42 CVEs with a maximum CVSS of 8.8. The most likely of them to be attacked is CVE-2026-42825, which FIRST.org rates at 80% probability of exploitation in the next 30 days.
Update summary
Fixes 42 CVEs. Most severe CVSS 8.8 (High). EPSS exploit probability up to 4.7%. Among the top 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.
Microsoft documents 1 known issue with this update.
- Windows Server Update Services (WSUS) does not display error details
KB5078737 is the May 2026 update for Windows 10 1809 and Windows Server 2019, rolling up fixes for 42 CVEs with a highest Severity of High (CVSS 8.8). None of the included CVEs are in the CISA KEV catalog or linked to ransomware, and the highest EPSS is only 4 percent, so this is a routine bulk patch rather than an emergency. The scale matters more than the urgency here: 42 distinct fixes across a legacy client and a still-common server platform.
Do this: Schedule KB5078737 in your next standard patch window for all 1809 and Server 2019 hosts, prioritizing internet-facing Server 2019 systems.
AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for KB5078737
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for KB5078737
- Released
- 2026-05-12
- Last changed
- 2026-07-24
- Changes tracked
- 2
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 KB5078737 is installed
Elevated PowerShell. No output means it is not installed.
Known issues, from Microsoft
Quoted from Microsoft's support article for KB5078737 (checked 2026-08-05). Verify against the article before acting.
Windows Server Update Services (WSUS) does not display error details
After installing KB5070892 or later updates, Windows Server Update Services (WSUS) does not display synchronization error details within its error reporting. This functionality is temporarily removed to address the Remote Code Execution Vulnerability, CVE-2025-59287 .
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 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.