On January 13, 2026, Microsoft released patches addressing 113 vulnerabilities spanning a wide range of products including Windows OS components, Microsoft Office, SharePoint, SQL Server, and the Edge browser. Among these vulnerabilities, eight are classified as critical, with one already exploited in the wild (CVE-2026-20805, an information disclosure vulnerability in Desktop Window Manager) and another previously disclosed. A significant vulnerability is CVE-2026-20854, a remote code execution flaw in the Local Security Authority Subsystem Service (LSASS), reminiscent of past severe Windows vulnerabilities like the Blaster worm. This vulnerability requires the attacker to be authenticated but does not require elevated privileges, which lowers the barrier for exploitation within compromised environments. Other critical vulnerabilities affect Microsoft Office components, including remote code execution flaws in Excel, Word, and Office Click-To-Run, which could allow attackers to execute arbitrary code via crafted documents. SharePoint also has multiple important vulnerabilities, including remote code execution and information disclosure issues. The Edge browser vulnerability patched upstream by Chromium addresses insufficient policy enforcement in the WebView tag, enhancing browser security. Many elevation of privilege vulnerabilities affect core Windows components such as the Windows Kernel, Windows Management Services, and Windows File Explorer, potentially allowing attackers to escalate privileges after initial access. The Secure Boot mechanism has a certificate expiration bypass vulnerability, which could undermine system integrity if exploited. While Microsoft considers some vulnerabilities less likely to be exploited due to required authentication or complexity, the presence of active exploitation and disclosed vulnerabilities underscores the urgency of patching. The update also includes fixes for Azure-related components and Windows virtualization-based security features. Overall, this Patch Tuesday release is comprehensive and addresses a broad attack surface, requiring coordinated patch management and monitoring efforts.

European organizations face significant risks from these vulnerabilities due to widespread use of Microsoft products in enterprise environments, government agencies, and critical infrastructure sectors. The remote code execution vulnerabilities in LSASS and Microsoft Office components could allow attackers to execute arbitrary code, potentially leading to full system compromise, data theft, ransomware deployment, or lateral movement within networks. The active exploitation of the Desktop Window Manager information disclosure vulnerability increases the risk of reconnaissance and targeted attacks. Elevation of privilege vulnerabilities could enable attackers with limited access to gain administrative control, exacerbating the impact of initial breaches. The Secure Boot certificate expiration issue could undermine device trust and integrity, affecting endpoint security. Given the diversity of affected components, organizations could experience confidentiality breaches, integrity violations, and availability disruptions. The potential for exploitation without elevated privileges or with only authentication increases the threat surface, especially in environments with weak access controls or compromised credentials. Failure to promptly apply patches could result in increased incidents of cyber espionage, ransomware attacks, and disruption of business operations across Europe.

1. Prioritize immediate deployment of the January 2026 Microsoft patches across all affected systems, focusing first on critical vulnerabilities such as CVE-2026-20854 (LSASS RCE), CVE-2026-20805 (Desktop Window Manager information disclosure), and critical Office and SharePoint vulnerabilities. 2. Implement strict access controls and network segmentation to limit access to critical services like LSASS and Desktop Window Manager, reducing the risk of exploitation by authenticated attackers. 3. Enhance monitoring and logging for signs of exploitation, including unusual authentication attempts, privilege escalations, and anomalous Office document behavior. 4. Conduct targeted threat hunting for indicators of compromise related to the known exploited vulnerabilities, especially in environments with high-value assets. 5. Review and update endpoint protection and intrusion detection systems to recognize exploitation techniques associated with these vulnerabilities. 6. Educate users on the risks of opening unsolicited Office documents and implement email filtering to reduce phishing attack vectors. 7. Validate Secure Boot configurations and update certificates to prevent bypass due to expired certificates. 8. For organizations using Azure and virtualization features, ensure related components are patched and security configurations are hardened. 9. Maintain an up-to-date asset inventory to ensure no affected systems are overlooked during patching. 10. Coordinate with incident response teams to prepare for potential exploitation attempts following patch release.