Cloudflare incident on September 17, 2024

What this post added

This post details an incident on September 17, 2024, where Cloudflare inadvertently stopped announcing fifteen IPv4 prefixes due to an internal software error during a routine renumbering exercise. This led to a temporary outage for some Business plan websites. The post explains the background of the Addressing team's work on IP address management and renumbering, the specific software bug that caused the failure (related to legacy SSL configurations and incomplete website renumbering), the incident timeline, and the immediate fix (rollback). It also outlines preventative measures including enhanced testing for outstanding assignments, improved verification processes for prefix withdrawals, and a review of legacy system functions.