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One regex took Cloudflare offline

Name: One regex took Cloudflare offline
Uploaded: 2026-10-27T07:52:02.000Z
Duration: 2 min 36 s
Channel: Himanshu Kukreja
Description: How a new firewall rule in simulate mode hit catastrophic backtracking, maxed out the CPUs serving web traffic across Cloudflare's whole network and caused 27 minutes of outage on 2 July 2019.

How a new firewall rule in simulate mode hit catastrophic backtracking, maxed out the CPUs serving web traffic across Cloudflare's whole network and caused 27 minutes of outage on 2 July 2019.

01 · A rule meant only to watch

One rule, meant only to watch.

A rule meant only to watch

2 July 2019.