Designing Trustworthy AI Pipelines from Data to Deployment Part 1 — The Backdoor That Didn’t Need a Vulnerability In February 2024, JFrog’s security research team found something that should have changed how the industry thinks about model repositories overnight: more than 100 malicious models sitting on Hugging Face, some carrying backdoors that gave an attacker remote access the moment someone loaded them ( JFrog, February 2024 ). The mechanism was almost embarrassingly simple: Python’s pickle serialization format — the default way PyTorch models get saved and loaded — executes arbitrary cod