Cloudflare outage on December 5, 2025

What this post added

This post details a significant outage caused by changes to the WAF's body parsing logic and internal testing tools. It highlights how an attempt to protect customers against a React Server Components vulnerability led to a critical error in the FL1 proxy when an internal WAF testing tool was disabled. The incident underscores the challenges of managing global configuration changes and the need for more robust deployment and error handling mechanisms, especially in the context of security-related updates. It also emphasizes the ongoing work to improve resiliency following a previous outage.