Discover how a Cloudflare WAF bypass in /.well-known/acme-challenge/ exposed origins, its impact, and the fix. A must-read for security pros.

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A zero-day vulnerability in Cloudflare's WAF allowed attackers to bypass security rules and access origin servers globally through the /.well-known/acme-challenge/ path. The vulnerability exploited the ACME HTTP-01 certificate validation mechanism, exposing protected origins despite WAF protections. Cloudflare has since patched the issue, but the discovery highlights critical security considerations for certificate validation paths and WAF rule configurations.

Cloudflare Zero-day: Accessing Any Host Globally