At one of the companies I worked at, years ago, a service discovery system I wrote did a very light scan of every listening port bound on every system. One thing it did was an HTTP GET.

One of the core apps had a control port that implemented HTTP. Unfortunately, my GET hit a route that didn't exist, and that caused a small memory leak every time.

Nothing too bad happened; the leak was slow, and even though the app stayed up many months at a time, we did notice the leak and figured out what was causing it.

As others have stated elsewhere, I've seen completely 'easy going' TCP connections to embedded devices cause immediate crashes.