In `api-gateway` versions till `1.7.3`, The default rate-limit key resolver, `ClientIpKeyResolver`, derives the per-client bucket key from the leftmost element of the `X-Forwarded-For` request header. That element is supplied by the originating HTTP client and is not validated against any trusted-proxy list. A single attacker can therefore obtain an unlimited number of independent rate-limit buckets — one per unique header value — and completely bypass the gateway's request-rate limiting on every route that uses the shipped default configuration.