The development of machine learning (ML) techniques has led to ample
opportunities for developers to develop and deploy their own models. Hugging
Face serves as an open source platform where developers can share and download
other models in an effort to make ML development more collaborative. In order
for models to be shared, they first need to be serialized. Certain Python
serialization methods are considered unsafe, as they are vulnerable to object
injection. This paper investigates the pervasiveness of these unsafe
serialization methods across Hugging Face, and demonstrates through an
exploitation approach, that models using unsafe serialization methods can be
exploited and shared, creating an unsafe environment for ML developers. We
investigate to what extent Hugging Face is able to flag repositories and files
using unsafe serialization methods, and develop a technique to detect malicious
models. Our results show that Hugging Face is home to a wide range of
potentially vulnerable models.