HTTP Request Smuggling

The HTTP Request Smuggling attack explores an incomplete parsing of the submitted data done by an intermediary HTTP system working as a proxy. HTTP Request Smuggling consists of sending a specially formatted HTTP request that will be parsed in a different way by the proxy system and by the final system, so the attacker could smuggle a request to one system without the other being aware of it. This attack makes it possible to exploit other attacks, like Cache Poisoning, Session Hijacking, Cross-site Scripting (XSS) and most importantly, the ability to bypass web application firewall protection.