CVE-2026-42266: Jupyter Jupyterlab

High severity, CVSS 8.8. EPSS: 0.9% chance of exploitation in the next 30 days.

JupyterLab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture. From 4.0.0 to 4.5.6, the allow-list of extensions that can be installed from PyPI Extension Manager (allowed_extensions_uris) is not correctly enforced by JupyterLab. The PyPI Extension Manager was not contained to packages listed on the default PyPI index. This vulnerability is fixed in 4.5.7.

Affected products

• Jupyter Jupyterlab: from 4.0.0, before 4.5.7 (fixed in 4.5.7)

Published 2026-05-13. Last modified 2026-08-28.