To be fair, "middleware" (in the Laravel sense) is really just any component that modifies or reacts to the HTTP layer between the Controller's processing of the request and the response. In this regard CodeIgniter has a lot of middleware already, we just don't call it that. `Filters` (linked above) is probably the most explicit version of what this original question was asking about. There are also tons of modules published by the community that add some additional "middleware" like authentication. Head over to he AddIns forum, or you can peruse some of my modules:
https://github.com/tattersoftware/
