# Cloudflare outage on November 18, 2025

<https://blog.cloudflare.com/18-november-2025-outage/>

- Host: [blog.cloudflare.com](https://links.thingelstad.xyz/hosts/blog.cloudflare.com/)
- Saved: November 19, 2025 (2025-11-20T01:28:46Z)
- Record: https://links.thingelstad.xyz/links/5271fc17f5fd/
- JSON: https://links.thingelstad.xyz/links/5271fc17f5fd.json

## What Jamie wrote

Cloudflare had a big outage on Monday morning that disrupted many services. Cloudflare is not a well known name to most but they are probably the largest CDN (content distribution network) in the world and they operate as a caching front-end for many websites. I have a lot of respect for the stuff they do — they are truly solving unique and very difficult engineering problems to scale the Internet and web even more.  This outage was rare and as is often the case the cause was frustrating banal.

> **The issue was not caused, directly or indirectly, by a cyber attack or malicious activity of any kind.** Instead, it was triggered by a change to one of our database systems' permissions which caused the database to output multiple entries into a "feature file" used by our Bot Management system. That feature file, in turn, doubled in size. The larger-than-expected feature file was then propagated to all the machines that make up our network.
> 
> The software running on these machines to route traffic across our network reads this feature file to keep our Bot Management system up to date with ever changing threats. The software had a limit on the size of the feature file that was below its doubled size. That caused the software to fail.

This is the kind of thing that can cause you massive issues and it seems so simple. Very specific issue, but the automation that allows the scale they operate takes anything and spreads it everywhere instantly. While physical isolation of infrastructure for survivability is very often clearly in place, the logical isolation of the software that that isolated physical infrastructure uses is a whole different issue. 

The observation that their status page was also down and it just being a coincidence seems almost too random to believe, but I guess. Lastly, it is impressive that Matthew Prince, CEO and Founder, wrote the incident report.

## Facts

- Kind: [Page](https://links.thingelstad.xyz/kinds/page/)

## Appears in

- [WT333: Weekly Thing 333 / Gemini, LangChain, Illusion](https://weekly.thingelstad.com/archive/333/), Notable

## Same host

- [Cloudflare’s 2025 Annual Founders’ Letter](https://links.thingelstad.xyz/links/de6b09150048/) (blog.cloudflare.com, September 25, 2025)
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## Elsewhere

- Wayback Machine: https://web.archive.org/web/*/https://blog.cloudflare.com/18-november-2025-outage/