Microsoft's October 2026 Patch Tuesday updates addressed 1,413 vulnerabilities, including 1,102 in Windows, 134 in Office applications, 61 in developer tools, and 36 related to SharePoint Server. This total surpasses the vulnerabilities fixed by Microsoft in all of 2025, with over 4,000 vulnerabilities resolved in 2026. A critical zero-day vulnerability, CVE-2026-96951, with a CVSS score of 8.8, was also patched; it allows attackers to bypass Windows shell security features. The Cybersecurity and Infrastructure Security Agency (CISA) has included this vulnerability in its Known Exploited Vulnerabilities catalog. Additionally, two publicly disclosed vulnerabilities were patched, and Microsoft introduced 'risk cohorts' to help manage security updates.