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Microsoft Windows 11 mandatory Patch Tuesday updates (KB5089549, KB5087420)

Security Patch Release
First reported
Last updated
Happening score
H score 29
1 unique sources, 1 articles

Summary

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Microsoft released mandatory Windows 11 cumulative updates for KB5089549 and KB5087420, delivering the May 2026 Patch Tuesday fixes for 120 vulnerabilities across 25H2/24H2 and 23H2. The release is a broad security patch bundle rather than a single-CVE fix, and it also includes bug fixes and feature changes. Systems on the affected Windows 11 versions should treat the update as a high-priority security deployment.

Related Happenings

Microsoft security patch release for CVE-2026-41091 and CVE-2026-45498

Security Patch Release
First: 21.05.2026 10:49 Last: 21.05.2026 10:49 Sources 1

About this happening: Microsoft rolled out security updates for Defender and related malware protection components to address two zero-days: CVE-2026-41091 and CVE-2026-45498. The fixes cover affected...

Latest development: 21.05.2026 12:52

Microsoft released patches for Microsoft Defender Antimalware Platform version 4.18.26040.7 to address CVE-2026-41091, a link-following privilege-escalation flaw that can let an authorized attacker elevate privileges locally to System, and CVE-2026-45498, a denial-of-service flaw. Microsoft said both vulnerabilities were publicly disclosed and exploited in the wild as zero-days. CISA added both flaws to its Known Exploited Vulnerabilities (KEV) list and urged federal agencies to patch them by June 3.

Open Happening

Windows BitLocker YellowKey mitigation guidance (CVE-2026-45585)

Advisory/Mitigation
First: 20.05.2026 10:31 Last: 20.05.2026 10:31 Sources 1

About this happening: Microsoft issued **mitigation guidance** for **YellowKey**, a **Windows BitLocker zero-day** that can expose **BitLocker-protected drives** before the security update is available...

Open Happening

Microsoft Windows 11 KB5089549 cumulative update

Security Patch Release
First: 18.05.2026 11:33 Last: 18.05.2026 11:33 Sources 1

About this happening: Microsoft's **KB5089549** **Windows 11** security update is failing to install on some systems, forcing affected devices to roll back during reboot. The problem is tied to a nearl...

Open Happening

Microsoft adds Cloud-Initiated Driver Recovery for Windows Update driver rollbacks

Security Tool/Service
First: 15.05.2026 15:29 Last: 15.05.2026 15:29 Sources 1

About this happening: Microsoft is adding **Cloud-Initiated Driver Recovery** to **Windows Update**, giving it a remote rollback control for **problematic Windows drivers**. The capability reduces how...

Open Happening

Microsoft May 2026 Patch Tuesday release

Security Patch Release
First: 13.05.2026 13:36 Last: 13.05.2026 13:36 Sources 1

About this happening: Microsoft's **May 13, 2026 Patch Tuesday** release fixed **138 vulnerabilities** across its product portfolio, including **Windows**, **Azure**, and **Edge**. None of the flaws we...

Open Happening

Timeline

  1. 12.05.2026 21:09 2 articles · 15d ago

    Microsoft releases Windows 11 KB5089549 and KB5087420

    Initial Disclosure

    On May 12, 2026, Microsoft released mandatory Windows 11 cumulative updates KB5089549 and KB5087420 for 25H2/24H2 and 23H2, bundling the May 2026 Patch Tuesday fixes for 120 vulnerabilities and delivering the same fixes across the supported Windows 11 versions.

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