The Cloud Metadata Attack exploits misconfigured NGINX servers to access instance metadata provided by cloud service providers like AWS, GCP, and Azure. These providers expose metadata through the internal, unroutable IP address ‘169.254.169.254’. If NGINX servers are incorrectly configured, this metadata can be accessed by including the IP address in the Host header field.
Ensure that NGINX configurations do not rely on user-controlled data, specifically the Host header variable, which can be manipulated by attackers.