I have recently read a post about vulnerability of Python pickle
module which allows to execute arbitrary Python code on unpickling: https://intoli.com/blog/dangerous-pickles/
The docs are suggesting to "never unpickle data received from an untrusted or unauthenticated source" but I can think of a hazard coming from supposedly trusted (but compromised) source.
As Python is a flexible, dynamic language it does not require a wizard to create an old-school computer virus infecting pickles.
Are there any known cases of such viruses?
[EDIT]
By "a virus" I mean literally old good "computer virus": a program that proliferates by adding itself to other programs.