Cloudflare · infra · fg-0012

curl to a Cloudflare-proxied site gets 403 'Just a moment...' with a short User-Agent

HTTP 403 with a Just a moment... page

Verified 2026-09-22 · Confirmed by 0 builders · Trust 50/100

Cause

Requests with a bare 'Mozilla/5.0' User-Agent or a default library agent get a Managed Challenge or a browser signature block. It looks like the page is down when it is not.

Fix

Send a full, realistic browser User-Agent when testing or scripting against the site. Never conclude a URL is 404 from a 403. Note: scripts calling any Cloudflare-fronted API, not only zones on the plan named below, can instead get error code: 1010 (a browser signature block) for a default library User-Agent; the same fix applies.

Apply

curl -A "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/139.0.0.0 Safari/537.36" https://example.com/

Affects: Cloudflare Pro zone, August and September 2026

Have your agent know this before it fails

claude mcp add --transport http footgun https://getfootgun.com/api/mcp