A defective update to CrowdStrike's Falcon security sensor crashed an estimated 8.5 million Windows computers around the world, producing the largest IT outage in history. Airlines grounded flights, hospitals postponed procedures, broadcasters went dark, and payment systems failed — all from a single flawed configuration file.

The incident was a stark demonstration of concentration risk in enterprise software: a widely deployed security agent running at the kernel level meant one vendor's mistake could cascade globally within minutes. Microsoft estimated the scale; the economic damage ran into the billions.

For startups selling into the enterprise, the outage sharpened buyers' focus on resilience, staged rollouts, and vendor concentration — themes that would echo through security procurement for the rest of the cycle.