This one might be hard to find using the author’s approach of throwing everything at various builds of ssh.
It is not really that hard to find in the wild if you had a device built this way, when overflowing buffers on embedded devices is a standard attack vector.
It might be hard to root cause, but it would not be that hard to find.
Finding more and more that these complex bugs people gloss over like you are now are being used in exploit chains and the end result is still my clients getting hacked