Microsoft October 2026 Patch Tuesday fixes 1,411 flaws, 3 zero-days

Microsoft's October 2026 Patch Tuesday addressed a record-breaking 1,411 vulnerabilities, including three zero-days — one of which was already being actively exploited in the wild via a Windows Shell security feature bypass. The .NET Framework bypass (CVE-2026-108398) is particularly dangerous as it allows unauthorized applications to execute while evading Windows Defender Application Control, a critical last-line defense. The sheer volume of vulnerabilities highlights the growing complexity of modern software ecosystems and the mounting pressure on security teams to triage and apply patches at scale. Delayed patching — especially for actively exploited zero-days — dramatically increases the window of opportunity for threat actors to compromise systems before defenses are updated.