The Miami Glitch: How a Single Config Error Leaked Cloudflare’s IPv6 Routes to the Global Internet

Cloudflare published a technical post‑mortem of a 25‑minute BGP route leak on 2026‑01‑22 that affected IPv6 traffic: an accidental deletion of a prefix list made the export policy overly permissive and caused internal IPv6 prefixes to be advertised to external peers, producing network congestion, packet loss and an estimated aggregate throughput loss of about 12 Gbps. Engineers manually reverted the configuration and halted automation to stop the leak; proposed mitigations include stricter export safeguards, CI/CD policy validation, improved detection, and adoption of RFC 9234 and RPKI ASPA.