I have just been reading more detailed about the recent CVE-2016-5696 vulnerability in linux kernels (version 3.6 and abov) at http://lwn.net/Articles/696868/ and there it tells that via an attack using the "challange ACK" side channel, data can be malicously injected into a TCP connection (e.g. a HTTP response/request).
I do not completely get the point, since I have always assumed that of course data can be injected/modified in a HTTP connection, because it is not encrypted to start with.
Am I right in assuming that the difference here is that this bug allows someone to inject data into a TCP connection, while not being a relaying node of that TCP connection (something they maybe phrasing off-path)?
Put more simply, is it wrong to say that essentially the CVE-2016-5696, consitutes a thread (malicious injection) which anyway existed, given tha the "on-path" relaying computer always had the change to alter content (if not prevented by encryption TLS/SSL)?