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

Microsoft's October 2026 Patch Tuesday addresses 1,411 vulnerabilities, including three zero-day flaws actively exploited or publicly disclosed. One actively exploited zero-day is CVE-2026-96951, a Windows Shell security feature bypass that allows command injection and enables attackers to bypass Mark of the Web protections. The other two zero-days are CVE-2026-108398, a .NET Framework security feature bypass that can bypass Windows Defender Application Control, and CVE-2026-92707, a denial-of-service flaw in MessagePack-CSharp. These updates are critical for preventing unauthorized code execution and privilege escalation.

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