Fast Facts
- Microsoft’s May 2026 security update patched 137 CVEs, including critical and high-severity flaws, yet for the first time in nearly two years, no actively exploited zero-day vulnerabilities were reported.
- Notable vulnerabilities include two in Microsoft Word’s Preview Pane (CVSS 8.4), which can lead to remote code execution without user interaction.
- The update also addressed nine high-severity vulnerabilities (scores ≥ 9.0), with three near-maximum severity, notably an RCE flaw in Microsoft Dynamics 365 and critical bugs in Azure services.
- Organizations are urged to prioritize patches, especially for flaws like the Netlogon RCE and AI-related vulnerabilities, amidst rising exposure from AI tools and increasing number of CVEs.
Patch Tuesday Brings No Zero-Days but Plenty of Fixes
This month marks an unusual milestone for Microsoft. For the first time in nearly two years, the company’s security update did not include any actively exploited zero-day vulnerabilities. This is good news because it means hackers currently have no new, high-priority flaws to target. Instead, the May 2026 update focused on fixing 137 different security issues, known as CVEs. Among these, 13 are considered likely to be exploited, and nine are rated as critical. These critical bugs include two vulnerabilities in Microsoft Office Word, which can be exploited through the Preview Pane. Experts warn that even one malicious email can put a system at risk without any user action.
While it’s reassuring to see no zero-day threats, the update still emphasizes the importance of patching. The sheer number of vulnerabilities shows that Microsoft continues to face constant security challenges. Tech researchers believe this trend might continue, especially with the help of artificial intelligence (AI). AI tools now assist security teams in finding flaws faster and more accurately. Consequently, future updates could be even larger, containing more fixes to keep systems safe and running smoothly. Keeping software up to date remains one of the best ways to protect ourselves from cyber threats.
High-Severity Vulnerabilities Highlight Ongoing Risks
Despite a quieter month, the update reveals some particularly dangerous flaws. Nine vulnerabilities scored 9.0 or higher on the severity scale, and three scored near the maximum of 9.9. One of the most pressing issues is a remote code execution (RCE) flaw in Microsoft Dynamics 365 On-premises. This flaw allows hackers to run malicious code without user permission. Experts recommend patching this vulnerability immediately because it can give hackers access to sensitive data like customer records and financial information.
Other serious flaws exist in Azure services. Two of these, with a severity score of 9.9, involve Azure Logic Apps and Azure Managed Instance for Apache Cassandra. Fortunately, Microsoft has already fixed these issues, and users do not need to take further action. However, the high severity of these bugs highlights how cloud services are attractive targets for hackers. Additionally, a severe flaw in Windows Netlogon can enable attackers to hijack domain controllers, which are vital for managing network security. Security researchers advise organizations to stay vigilant, monitor abnormal network activity, and apply patches as soon as possible. The growth of AI-based vulnerabilities in tools like Copilot and Azure AI also underscores the expanding risk landscape for organizations worldwide.
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