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CVE-2026-42557

9.6 · CRITICAL

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

Published May 13, 2026CWE-79EPSS 0.71%

Overview

CVE-2026-42557 is a critical-severity vulnerability. It was published on May 13, 2026 and has a CVSS 3.1 base score of 9.6 (CRITICAL).

This vulnerability has a CVSS 3.1 base score of 9.6, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

jupyterlab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture. Prior to 4.5.7, JupyterLab's HTML sanitizer allowlists data-commandlinker-command and data-commandlinker-args on button elements, while CommandLinker listens for all click events on document.body and executes the named command without checking whether the element came from trusted JupyterLab UI. A notebook with a pre-saved HTML cell output containing a deceptive button can trigger arbitrary JupyterLab commands - including arbitrary code execution - on a single user click, without any code being submitted for execution by the user. 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/security/advisories/GHSA-mqcg-5x36-vfcgRefaccess.redhat.com/errata/RHSA-2026:43038Refaccess.redhat.com/errata/RHSA-2026:60520Refaccess.redhat.com/security/cve/CVE-2026-42557Refbugzilla.redhat.com/show_bug.cgi?id=2477086Refsecurity.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42557.json

How CyberStrike helps

Frequently asked questions

What is CVE-2026-42557?

CVE-2026-42557 is a critical-severity vulnerability. It was published on May 13, 2026 and has a CVSS 3.1 base score of 9.6 (CRITICAL).

How severe is CVE-2026-42557?

This vulnerability has a CVSS 3.1 base score of 9.6, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-42557?

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-2026-42557?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-42557 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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