Patch tracker / KB5089466

KB5089466: Windows 11 Version 25H2 for x64-based Security Update (June 2026)

KB5089466 is a Critical security update for Windows 11 Version 25H2 for x64-based , released 2026-06-09. It closes 61 CVEs with a maximum CVSS of 9.8. The most likely of them to be attacked is CVE-2026-48566, which FIRST.org rates at 80% probability of exploitation in the next 30 days.

Update summary

Critical
2026-06-09
Released
61
CVEs fixed
9.8
Max CVSS
Critical
Severity
Deploy this cycle
Fixes 61 CVEs for Windows 11 Version 25H2 for x64-based . No confirmed in-the-wild exploitation in this set today.

Fixes 61 CVEs. Most severe CVSS 9.8 (Critical). EPSS exploit probability up to 4.7%. Among the top half of tracked Microsoft updates by EPSS exploit probability.

Senserva found thisread these before you deploy broadly

Microsoft documents 1 known issue with this update.

  • Microsoft is not currently aware of any issues with this update.

The full text, quoted from Microsoft

Microsoft Update Catalog: download KB5089466Microsoft support article
Senserva AI Opinion for KB5089466

KB5089466 is a large June 2026 rollup for Windows Server 2025 Server Core and Windows 11 25H2 on ARM64 and x64, closing 61 CVEs including one rated Critical at CVSS 9.8. The severity comes from the aggregate, but the top EPSS across these CVEs is only 5 percent and none appear in CISA KEV or are tied to ransomware. Server Core hosts and 25H2 fleets are directly in scope.

Do this: Schedule KB5089466 across your Windows 11 25H2 and Server 2025 Core systems this cycle, prioritizing the Critical CVSS 9.8 CVE.

AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for KB5089466

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

Full tracking and change history for KB5089466

Released
2026-06-09
Last changed
2026-06-09
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 KB5089466 is installed

Elevated PowerShell. No output means it is not installed.

Known issues, from Microsoft

Quoted from Microsoft's support article for KB5089466 (checked 2026-08-05). Verify against the article before acting.

Microsoft is not currently 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.

CVESeverityCVSSEPSSExploited
CVE-2025-54518Critical9.880%No
CVE-2026-21530Critical9.880%No
CVE-2026-32161Critical9.880%No
CVE-2026-32170Critical9.880%No
CVE-2026-32209Critical9.880%No
CVE-2026-33834Critical9.880%No
CVE-2026-33835Critical9.880%No
CVE-2026-33837Critical9.880%No
CVE-2026-33838Critical9.880%No
CVE-2026-33839Critical9.880%No
CVE-2026-33840Critical9.880%No
CVE-2026-33841Critical9.880%No
CVE-2026-34329Critical9.880%No
CVE-2026-34330Critical9.880%No
CVE-2026-34331Critical9.880%No
CVE-2026-34333Critical9.880%No
CVE-2026-34334Critical9.880%No
CVE-2026-34336Critical9.880%No
CVE-2026-34337Critical9.880%No
CVE-2026-34338Critical9.880%No
CVE-2026-34339Critical9.880%No
CVE-2026-34340Critical9.880%No
CVE-2026-34341Critical9.880%No
CVE-2026-34342Critical9.880%No
CVE-2026-34343Critical9.880%No
CVE-2026-34344Critical9.880%No
CVE-2026-34345Critical9.880%No
CVE-2026-34347Critical9.880%No
CVE-2026-34351Critical9.880%No
CVE-2026-35415Critical9.880%No
CVE-2026-35416Critical9.880%No
CVE-2026-35417Critical9.880%No
CVE-2026-35418Critical9.880%No
CVE-2026-35419Critical9.880%No
CVE-2026-35421Critical9.880%No
CVE-2026-35422Critical9.880%No
CVE-2026-35423Critical9.880%No
CVE-2026-35424Critical9.880%No
CVE-2026-40369Critical9.880%No
CVE-2026-40377Critical9.880%No
CVE-2026-40380Critical9.880%No
CVE-2026-40382Critical9.880%No
CVE-2026-40397Critical9.880%No
CVE-2026-40398Critical9.880%No
CVE-2026-40399Critical9.880%No
CVE-2026-40401Critical9.880%No
CVE-2026-40403Critical9.880%No
CVE-2026-40405Critical9.880%No
CVE-2026-40406Critical9.880%No
CVE-2026-40407Critical9.880%No
CVE-2026-40408Critical9.880%No
CVE-2026-40410Critical9.880%No
CVE-2026-40413Critical9.880%No
CVE-2026-40414Critical9.880%No
CVE-2026-40415Critical9.880%No
CVE-2026-41088Critical9.880%No
CVE-2026-41096Critical9.880%No
CVE-2026-41097Critical9.880%No
CVE-2026-42825Critical9.880%No
CVE-2026-42896Critical9.880%No
CVE-2026-48566Critical9.880%No

Scope and sources

Affected products
Also released in June 2026

KB5094139

8 CVEs · High · exploited

KB5094140

8 CVEs · High · exploited

KB5094142

8 CVEs · High · exploited

KB5094144

8 CVEs · High · exploited

KB5087423

66 CVEs · Critical

KB5087539

66 CVEs · Critical

KB5089549

61 CVEs · Critical

KB5093998

158 CVEs · Critical

The full month, summarized: Microsoft Patch Tuesday.

Authoritative references
Official KB5089466 page (Microsoft Support)Microsoft Update CatalogMicrosoft Security Update Guide

See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.

New to a term on this page? CVE, KB, KEV, CVSS, and EPSS are each explained once, on the Senserva security lexicon. Reference: Microsoft CVE and vulnerability management and the Microsoft patching guide.
Provided as is, without warranty; verify against the vendor advisory before acting. Data notice and terms.