org.springframework.cloud:spring-cloud-gateway-server-mvc@4.2.7

Affected versions of this package are vulnerable to Use of Less Trusted Source. Spring Cloud Gateway Server forwards the X-Forwarded-For and Forwarded request headers it receives from untrusted proxies to downstream services. Both the WebFlux and WebMVC Gateway Servers process these headers via their forwarded-header filters (e.g. XForwardedHeadersFilter / ForwardedHeadersFilter and, in WebFlux, the NettyServerCustomizer), but when no trusted-proxy configuration is present the gateway does not strip the incoming headers before proxying the request. An attacker who can reach the gateway can therefore send a forged X-Forwarded-For or Forwarded header that the gateway passes through unchanged to backend services. Downstream applications that trust these headers for client-IP-based access control, rate limiting, audit logging, or geolocation can be misled, enabling IP allowlist/denylist bypass, source-address spoofing, and log forgery.

Note:

This is only exploitable in certain configuration scenarios: when forwarded-header handling is enabled but the trusted proxy property is not set (so the gateway has no basis to distinguish trusted from untrusted proxies), or when relying on the WebFlux NettyServerCustomizer.

Upgrade org.springframework.cloud:spring-cloud-gateway-server-mvc to version 4.3.5 or higher.