Microsoft Patches 1,413 Security Vulnerabilities in Record-Breaking October Update

Microsoft released its largest-ever security update in October 2026, patching 1,413 vulnerabilities across its products, including an actively exploited Windows zero-day flaw.

Security researchers called it the biggest single Patch Tuesday in Microsoft's history. The company releases security patches on the second Tuesday of each month, a practice known as Patch Tuesday.

The actively exploited zero-day affected Windows and was being used in attacks before Microsoft had a fix available. The company did not disclose details about who was exploiting the vulnerability or what targets were affected.

The record-breaking update comes as Microsoft continues to push artificial intelligence features into its products, including its Surface laptop lineup and the Copilot Health assistant. Security experts say the growing complexity of Microsoft's software stack, combined with the integration of AI components, has expanded the attack surface that needs to be protected.

The update also addressed vulnerabilities in Microsoft Office, Azure cloud services, and the Edge browser.

Security professionals recommend that organizations apply the patches as quickly as possible, particularly for the zero-day flaw. Businesses running older versions of Windows that no longer receive security updates are advised to upgrade to supported versions.

The October update follows a September release that also addressed a significant number of vulnerabilities, continuing a trend of large monthly patch releases in 2026.