Microsoft Rings in 2025 With Record Security UpdateMicrosoft Rings in 2025 With Record Security Update

Microsoft’s January update contains patches for a record 159 vulnerabilities, including eight zero-day bugs, three of which attackers are already actively exploiting.

The update is Microsoft's largest ever and is notable also for including three bugs that the company said were discovered by an artificial intelligence (AI) platform.  

Microsoft assessed 10 of the vulnerabilities disclosed this week as being of critical severity and the remaining ones as important bugs to fix. As always, the patches address vulnerabilities in a wide range of Microsoft technologies, including Windows OS, Microsoft Office, .NET, Azure, Kerberos, and Windows Hyper-V.

They include more than 20 remote code execution (RCE) vulnerabilities, nearly the same number of elevation-of-privilege bugs, and an assortment of other denial-of-service flaws, security bypass issues, and spoofing and information disclosure vulnerabilities.

Three Vulnerabilities to Patch Immediately

Multiple security researchers pointed to the three actively exploited bugs in this month's update as the vulnerabilities that need immediate attention. The vulnerabilities, identified as CVE-2025-21335, CVE-2025-21333, and CVE-2025-21334, are all privilege escalation issues in a component of the Windows Hyper-V’s NT Kernel.

Related:A History of Microsoft Azure Outages

Attackers can exploit the bug relatively easily and with minimal permissions to gain system-level privileges on affected systems.

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