HTTP Status Codes

407 Proxy Authentication Required

Like 401, but the authentication is demanded by an intermediary proxy rather than the origin server, via the Proxy-Authenticate header.

What it means

407 Proxy Authentication Required is returned by a proxy that needs credentials before forwarding the request. The response carries a Proxy-Authenticate header, and the client replies with Proxy-Authorization. It is the proxy-layer analogue of 401.

Why it matters

  • It lets corporate and gateway proxies enforce authentication distinctly from origin auth.

Common mistakes

  • Confusing 407 (proxy) with 401 (origin) when debugging authentication failures.

How WebInspect checks this

  • WebInspect surfaces proxy-related headers and the status when an intermediary challenges the request.