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CVE-2026-42266

8.8 · HIGH

JupyterLab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture.

Published May 13, 2026CWE-88EPSS 0.85%

Overview

CVE-2026-42266 is a high-severity vulnerability. It was published on May 13, 2026 and has a CVSS 3.1 base score of 8.8 (HIGH).

This vulnerability has a CVSS 3.1 base score of 8.8, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/jupyterlab/jupyterlab/releases/tag/v4.5.7GitHubgithub.com/jupyterlab/jupyterlab/security/advisories/GHSA-37w4-hwhx-4rc4Refjupyterhub.readthedocs.io/en/5.2.1/explanation/websecurity.htmlRefjupyterlab.readthedocs.io/en/latest/user/extensions.html#extension-manager-implementationsRefaccess.redhat.com/errata/RHSA-2026:43038Refaccess.redhat.com/errata/RHSA-2026:60520Refaccess.redhat.com/security/cve/CVE-2026-42266Refbugzilla.redhat.com/show_bug.cgi?id=2477072Refsecurity.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42266.json

How CyberStrike helps

Frequently asked questions

What is CVE-2026-42266?

CVE-2026-42266 is a high-severity vulnerability. It was published on May 13, 2026 and has a CVSS 3.1 base score of 8.8 (HIGH).

How severe is CVE-2026-42266?

This vulnerability has a CVSS 3.1 base score of 8.8, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-42266?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-42266?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-42266 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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