A few years back I have heard from a lot of people working in ML communities that they are surprised that `numpy.load` is able to execute arbitrary code.
This is correct, before version 1.16.3 (April 2019) `numpy.load` was unsafe by default, unless explicitly specifying `allow_pickle=False`. However, to be clear, that unsafe default was then fortunately changed. Loading numpy arrays with `numpy.load` should now be safe (unless there are yet-to-be-found bugs in that code).
There have been dozens, if not _hundreds_, of CVEs filed on issues related to pickle and RCE.
Here is a small sample:
And BinaryFormatter has been long ago deprecated (and now it got completely removed, in the form of a breaking change, something that pretty much never happens otherwise), and even when it was in use (more than a decade ago, popularity-wise), the use of type binding was heavily encouraged.
E.g. My discovery the other day that out of the box C# System.Text.Json can't serialize System.Exception without writing a custom serializer [0] (since 2020, because .NET fix speed...). NewtonSoft handles it fine. (Had wanted a quick-and-dirty debugging dump of properties)
If you are okay with risks that come from including exception's message in data sent over the network (e.g. not publicly exposed), then defining a custom converter is trivial (it's like 10-15 lines and adding it to serializer options), or you could simply .ToString/.Message it and include that in the payload instead. It's a minute thing.
As for exception deserialization, that's a gross feature misuse and not something that should be done.
A serializer should generate a sane serialization of whatever I throw at it. Or at least have an option that allows me to force that.
If I then choose to send that serialization somewhere unreasonable, that's on me.
In my case, I was hacking in C#-on-top-of-another-environment, so didn't have full access to reimplement stuff, without jumping through additional hoops.
That said, absolutely agreed on de-serialization, as larger opportunities for footguns abound.