CrowdStrike outage (2024)
The largest IT outage in history: a broken update from a security vendor knocked out 8.5 million Windows machines in one morning, with no attacker involved.
On 19 July 2024, CrowdStrike pushed a content update to its Falcon sensor — "Channel File 291". The file carried one field more than the code expected, and the kernel module that parsed it performed an out-of-bounds read. Because the code runs in the kernel, it took the whole system down with it: a blue screen, then a boot loop the machine could not escape on its own.
Airlines grounded flights, hospitals paused, exchanges and broadcasters went dark. There was no fix to push remotely — each machine had to be booted into safe mode and the file deleted by hand. The uncomfortable moral: software meant to protect you, running in the kernel, has the same power to fell you as any malware, and an update shipped without staged rollout is its own attack vector.