Microsoft Patches 161 Flaws, Including Exploited Hyper-V Privilege Escalation Bugs
Active Exploitation · 2 sources · Updated 4mo ago · First seen Jan 24, 2026
Microsoft released its January 2025 security updates to fix 161 vulnerabilities across its product portfolio, including 58 remote code execution flaws and 12 critical issues. The update covers high-risk weaknesses in Windows OLE, Windows RMCAST, Windows NTLM v1, Azure Marketplace SaaS Resources, Microsoft Purview, Microsoft Excel, Remote Desktop Services, Digest Authentication, NEGOEX, and BranchCache, according to Microsoft’s release notes and CSIRT.SK.
The most urgent issues are three Windows Hyper-V NT Kernel Integration VSP privilege-escalation vulnerabilities — CVE-2025-21333, CVE-2025-21334, and CVE-2025-21335 — which were reported as actively exploited in the wild. Defenders were urged to deploy the January patch bundle quickly, with additional mitigations noted for some exposures, including using plaintext mode in Outlook, restricting exposed PGM ports, and disabling NTLMv1 by setting LmCompatibilityLevel to 5.
