Microsoft: Happy 2025. Here’s 161 Security Updates

Microsoft January 2025 Patch Tuesday: Key Highlights and Vulnerabilities
On January 14, 2025, Microsoft released a significant set of security updates as part of the January Patch Tuesday, addressing a total of 159 vulnerabilities across various Microsoft products. Here are the key highlights and details on the critical security updates and zero-day vulnerabilities:
Scope and Impact
- The January 2025 Patch Tuesday update is notable for being one of the largest in recent years, fixing the highest number of CVEs (Common Vulnerabilities and Exposures) in a single month since at least 20173.
Critical Vulnerabilities
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Remote Code Execution (RCE) Vulnerabilities:
- Several critical RCE vulnerabilities were addressed, including those in Microsoft Excel (CVE-2025-21362, CVE-2025-21354), Windows Remote Desktop Services (CVE-2025-21309, CVE-2025-21297), and the Reliable Multicast Transport Driver (RMCAST) (CVE-2025-21307)1.
- Vulnerabilities in Windows OLE (CVE-2025-21298) and BranchCache (CVE-2025-21296) also allow for remote code execution via crafted inputs1.
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Privilege Escalation:
- A critical vulnerability in Windows NTLM V1 (CVE-2025-21311) could allow attackers to escalate privileges, potentially gaining higher access levels on the system1.
- Three vulnerabilities in Windows Hyper-V (CVE-2025-21333, CVE-2025-21334, CVE-2025-21335) were fixed, which are being actively exploited. These allow authenticated users to execute code with SYSTEM privileges34.
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Authentication Mechanisms:
- Critical RCE vulnerabilities affecting authentication mechanisms such as SPNEGO and Digest Authentication (CVE-2025-21295, CVE-2025-21294) were also addressed1.
Zero-Day Vulnerabilities
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Hyper-V Zero-Days:
- Three zero-day vulnerabilities in Windows Hyper-V (CVE-2025-21333, CVE-2025-21334, CVE-2025-21335) were actively exploited. These vulnerabilities allow attackers to elevate their privileges to SYSTEM on compromised Windows and Windows Server machines34.
- These flaws involve a buffer overflow bug and use-after-free flaws in the NT Kernel component of Hyper-V4.
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Other Zero-Days:
Affected Products
- The updates affect a wide range of Microsoft products, including Windows clients and servers, Office, Azure, Hyper-V, SharePoint Server, .NET, Visual Studio, Remote Desktop Services, BitLocker, and the Windows Virtual Trusted Platform Module3.
Deployment and Recommendations
- The patches are cumulative for Windows 10 and Windows 11, including all security and non-security fixes up to the Patch Tuesday release2.
- Organizations using Hyper-V are particularly advised to prioritize the deployment of these patches due to the active exploitation of the Hyper-V vulnerabilities34.
Use of AI in Vulnerability Detection
- Notably, some of the vulnerabilities, including those in Microsoft Access, were discovered using AI-powered tools such as Unpatched.ai, highlighting the increasing role of automated vulnerability detection in security research4.
In summary, the January 2025 Patch Tuesday updates are significant due to the large number of vulnerabilities addressed and the presence of actively exploited zero-day vulnerabilities, particularly in Windows Hyper-V. These updates are crucial for maintaining the security and integrity of Microsoft products. For more detailed information, users can refer to the official Microsoft security update pages and additional resources from security researchers124.