Cloudflare outage, 18 November 2025

Cloudflare global outage from oversized Bot Management file (18 November 2025). The disruption lasted about 5 hours 46 minutes, according to Cloudflare’s own timeline.

What happened. A permissions change to a ClickHouse database made a query output duplicate rows into the Bot Management ‘feature file’, doubling its size. The file was propagated network-wide and exceeded a size limit in the core proxy software, which failed and served 5xx errors.

What changes. Cloudflare will harden ingestion of internally generated config files like user input, add more global kill switches, and review failure modes across core proxy modules.

Questions

What caused the Cloudflare outage in November 2025?

A permissions change to a ClickHouse database made a query output duplicate rows into the Bot Management ‘feature file’, doubling its size.

Which services were affected?

Core CDN and security services (HTTP 5xx), Turnstile, Workers KV, Dashboard login, Access, Email Security.

Read how shared dependencies spread a failure in why one cloud outage can break unrelated apps, or browse the outage archive.