# CVE-2026-42266

## Summary

- **CVE ID:** CVE-2026-42266
- **Severity:** HIGH
- **CVSS Score:** 8.8 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** CWE-88, CWE-602
- **Published:** May 13, 2026
- **Last Modified:** Aug 28, 2026

## Description

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

- jupyterlab — jupyterlab (>= 4.0.0, < 4.5.7)

## References

- [CNA](https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-37w4-hwhx-4rc4)
- [CNA](https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.7)
- [CNA](https://jupyterhub.readthedocs.io/en/5.2.1/explanation/websecurity.html)
- [CNA](https://jupyterlab.readthedocs.io/en/latest/user/extensions.html#extension-manager-implementations)
- [redhat-SADP](https://access.redhat.com/security/cve/CVE-2026-42266)
- [redhat-SADP](https://bugzilla.redhat.com/show_bug.cgi?id=2477072)
- [redhat-SADP](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42266.json)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:43038)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:60520)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.63%
- **EPSS Percentile:** 48.1

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._