A Jupyter notebook is a structured .ipynb file used for interactive computing, data analysis, and reproducible workflows. Unlike plain source code, it is a JSON document that can contain code cells, outputs, markdown, and metadata. That structure makes notebooks useful for collaboration, but it also makes them more complex to handle safely.
In cyber security, notebooks matter because servers, review tools, and converters may parse them automatically. Any parser that processes attacker-controlled notebook content becomes part of the attack surface, especially if it renders previews, builds diffs, or executes helper logic. Defenders should treat .ipynb files as untrusted input, keep notebook-handling components patched, and limit backend privileges so a parsing flaw cannot easily become remote code execution.