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Microsoft released fixes for 137 vulnerabilities across Windows, Azure, Microsoft 365, developer tools, and AI-related products, with no zero-days reported as exploited in the wild. The most urgent issues included a wormable pre-auth remote code execution flaw in Windows Netlogon (CVE-2026-41089), an unauthenticated RCE in the Windows DNS Client (CVE-2026-41096) that can be triggered through crafted DNS responses, and a remote code execution bug in Microsoft Dynamics 365 on-premises (CVE-2026-42898). Microsoft also patched an authenticated SharePoint Server RCE (CVE-2026-40365), multiple Microsoft Word Preview Pane RCEs, and a critical authentication bypass in the Microsoft SSO Plugin for Jira & Confluence (CVE-2026-41103).
The release was notable for its severity, with reports citing 16 to 30 critical vulnerabilities depending on classification, and 14 flaws scoring 9.0 or higher, including an Azure DevOps information disclosure issue rated CVSS 10.0 that Microsoft said had already been fully mitigated. Elevation-of-privilege bugs made up the largest share of fixes, spanning the Windows kernel, Win32k, TCP/IP, SMB Client, Print Spooler, and other core components; two locally exploitable issues, including Windows Print Spooler (CVE-2026-34342) and Windows Message Queueing (CVE-2026-33838), were publicly disclosed alongside patches. Microsoft said its AI-driven bug-finding system MDASH identified 16 of the vulnerabilities, and it separately warned enterprises to complete Secure Boot certificate updates before June 26, 2026, while noting a BitLocker Recovery issue on some Windows Server 2025 systems with an unrecommended Group Policy setting.
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11 events from the most recent confirmed update back to the earliest known activity.
Microsoft disclosed that its AI-based MDASH bug-hunting system identified 16 of the vulnerabilities included in the May 2026 Patch Tuesday release.
In conjunction with the May 2026 Patch Tuesday guidance, Microsoft reminded organizations of a deadline to apply Secure Boot certificate updates by June 26, 2026, and also noted a BitLocker Recovery issue affecting some Windows Server 2025 systems with an unrecommended Group Policy setting.
Coverage of the May 2026 release identified the most urgent patched issues as a wormable Windows Netlogon RCE affecting domain controllers, an unauthenticated Windows DNS Client RCE, and a Dynamics 365 on-premises RCE.
ZDI publicly disclosed CVE-2026-34342 on the same day Microsoft released a patch, describing a race condition in splwow64.exe that could let a low-privileged attacker escalate privileges.
ZDI publicly disclosed CVE-2026-33838 on the same day Microsoft released a fix, describing a double-free flaw in the mqac.sys driver that could lead to kernel-level code execution from low privileges.
As part of the May 2026 release, Microsoft said it had already fully mitigated a CVSS 10.0 Azure DevOps information disclosure vulnerability before or at disclosure time.
Microsoft issued its May 2026 Patch Tuesday security updates, fixing 137 vulnerabilities across Windows, Office, Azure, developer tools, AI products, and server components. Microsoft said no zero-days were publicly disclosed before release or known to be exploited in the wild.
Microsoft posted Security Update Guide entries for several Edge and Edge for Android issues, including CVE-2026-41107, CVE-2026-42891, CVE-2026-42838, and CVE-2026-35429.
Microsoft's Security Update Guide published CVE-2026-33821, an elevation of privilege vulnerability in Microsoft Dynamics 365 Customer Insights, ahead of the broader May Patch Tuesday release.
Researcher Marcin Wiazowski reported CVE-2026-34342, a Windows Print Spooler local privilege escalation vulnerability, to Microsoft through ZDI.
Zero Day Initiative reported CVE-2026-33838, a local privilege escalation flaw in Microsoft Windows Message Queueing, to Microsoft for coordinated disclosure.
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Microsoft’s May 2026 Patch Tuesday resolved between **120 and 137 vulnerabilities** across Windows, Office, networking services, Hyper-V, SharePoint Server, and Microsoft Dynamics 365 on-premises, including **17 to 30 critical flaws**. Microsoft said the release contained **no publicly disclosed or actively exploited zero-days**, but multiple high-risk issues affected core enterprise infrastructure. Notable vulnerabilities included unauthenticated remote code execution in **Windows Netlogon** (`CVE-2026-41089`) and the **Windows DNS Client** (`CVE-2026-41096`), a **Hyper-V guest-to-host escape**, a SharePoint Server RCE (`CVE-2026-40365`), and a **Dynamics 365 on-premises** RCE (`CVE-2026-42898`) rated **CVSS 9.9**. The update also addressed Office and endpoint attack paths, including Microsoft Word flaws and `CVE-2026-35421`, which could allow code execution through malicious **EMF** files opened in Microsoft Paint via Windows GDI. Security researchers said organizations should prioritize patching **domain controllers**, **DNS-exposed Windows systems**, **on-premises collaboration platforms**, and **user endpoints** because of their exposure and likely exploitability. Alongside the security fixes, Microsoft issued mandatory Windows 11 cumulative updates **KB5089549** and **KB5087420** for versions **25H2, 24H2, and 23H2**, adding platform changes such as File Explorer, accessibility, storage, printing, and secure batch file processing improvements.
Jun 29, 2026
Microsoft released its May Patch Tuesday updates fixing 137 vulnerabilities across Windows, Office, Azure, Dynamics 365, SharePoint, Copilot, and other products, with no actively exploited zero-days or publicly disclosed flaws reported at release. The update included multiple high-severity remote code execution bugs, notably Microsoft Word flaws `CVE-2026-40361` and `CVE-2026-40364`, which can be triggered through the Preview Pane by sending a malicious document, as well as `CVE-2026-42898` in Microsoft Dynamics 365 On-Premises, `CVE-2026-42823` in Azure Logic Apps, and `CVE-2026-33109` in Azure Managed Instance for Apache Cassandra. Researchers also flagged `CVE-2026-41089` in Windows Netlogon and `CVE-2026-41096` in Windows DNS Client as especially urgent because they expose broadly deployed enterprise infrastructure to remote compromise. Microsoft’s Windows 11 cumulative updates, including `KB5089549` and `KB5087420`, delivered many of the security fixes alongside reliability and usability improvements, and Microsoft said it was not aware of new issues with the release. Coverage and advisories also showed the breadth of the month’s attack surface, with additional fixes for SharePoint Server remote code execution, Office Click-to-Run privilege escalation, Hyper-V guest-to-host escalation, Teams spoofing, Outlook for iOS tampering, and several Copilot and Visual Studio Code vulnerabilities. Security researchers said the growing volume of Microsoft disclosures may reflect increased AI-assisted vulnerability discovery, while defenders were urged to prioritize patching domain controllers, DNS-exposed Windows systems, Office deployments, and internet-facing enterprise applications.
Jul 20, 2026
Microsoft released fixes for **163 vulnerabilities** in its April Patch Tuesday update, marking one of its largest security releases on record. The bundle includes **8 Critical** flaws, **154 Important** issues, and **1 Moderate** bug, with seven of the Critical vulnerabilities enabling remote code execution across products and components including **Windows TCP/IP**, **Windows IKE Service Extensions**, **Active Directory**, **Remote Desktop Client**, **Microsoft Office**, and **Microsoft Word**. Belgian authorities urged organizations to apply the updates immediately. The most urgent issues include **`CVE-2026-32201`**, an actively exploited **Microsoft SharePoint Server** vulnerability that was added to CISA’s Known Exploited Vulnerabilities catalog, and **`CVE-2026-33825`** in **Microsoft Defender**, a publicly disclosed zero-day tied to proof-of-concept code associated with the **BlueHammer** exploit. Microsoft also shipped Windows 11 cumulative updates with security hardening changes, including safer handling of **`.rdp`** files and improved visibility into **Secure Boot** certificates, while the broader patch set addressed numerous elevation-of-privilege and security feature bypass flaws that could support post-compromise escalation.
Jun 29, 2026