Microsoft's largest Patch Tuesday ever: 622 flaws, Kerberos encryptio…

Microsoft released 570 security patches in July 2026, including 59 critical flaws and three actively exploited zero-days across Windows, Office, Exchange, and Azure. The update also begins mandatory enforcement of Kerberos RC4 encryption phase-out, forcing organisations to upgrade legacy authentication systems. You now have a hard deadline to rip out legacy Kerberos from your Windows infrastructure—Microsoft isn't asking. If you're running old AD FS or domain controllers on RC4, plan your upgrade path this month or risk being forced into an emergency swap when RC4 stops working.