CVE-2026-42266

Name: CVE-2026-42266
Creator: NVD / NIST
Published: 2026-05-13T16:16:47.017+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.8/10EPSS 0.49%

Last modified Jun 17, 2026

CVE-2026-42266 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. 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. EPSS estimates a 0.49% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

8.8/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.49%

38.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Jupyter	Jupyterlab	>= 4.0.0, < 4.5.7

References

https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.7Patch, Release Notes
https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-37w4-hwhx-4rc4Mitigation, Vendor Advisory
https://jupyterhub.readthedocs.io/en/5.2.1/explanation/websecurity.htmlProduct
https://jupyterlab.readthedocs.io/en/latest/user/extensions.html#extension-manager-implementationsProduct

Timeline

Published: May 13, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-42266?

How severe is CVE-2026-42266?

CVE-2026-42266 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 0.49% probability of exploitation in the next 30 days.

How do I fix CVE-2026-42266?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-42266?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST