More on impedance mismatch
Recently there has been increased interest in the impedance mismatch problem, which occurs between multiple layers of a HTTP stack (e.g. proxy/security/web server) when they interpret HTTP differently. If you recall, I wrote about it in March. Shortly after Sverre talked about his worries: Incompatible Parameter Parsing. Then, a few days ago, Watchfire released a detailed analysis of how to smuggle two requests in a transaction where there should be only one: HTTP Request Smuggling. Finally, yesterday Amit Klein posted a message to the web security list, subtitled "A survey of new attacks on the less explored parts of the web application".
This topic is of great interest to security professionals that work with HTTP (who isn't nowadays!). The more we talk about it the greater the understanding of the strengths and the weaknesses of layered approach to application protection. To the end users, this is another clear message they should work to deploy secure applications in the first place.