High 8.8Published May 13, 2026

CVE-2026-42266JupyterLab has an Extension Manager API/GUI Policy Discrepancy allowing 3rd party (malicious) extensions install via POST request.

Updated under an hour ago (Oct 27, 2026, 6:40 PM ET)

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It affects jupyterlab and 3 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Exploited in the last 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.

CVSS: 8.8 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-88, CWE-602
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Modified
Record last updated: Aug 28, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

jupyterlab jupyterlab jupyterlab:jupyterlab (from the name)	from 4.0.0, < 4.5.7	CNA record
Red Hat Red Hat Migration Toolkit for Applications 8.2 redhat:migration_toolkit_applications	from 1784109883 not affected	CISA ADP
Red Hat Red Hat OpenShift AI 3.4 redhat:openshift_ai	from 1787076778 not affected	CISA ADP
jupyter jupyterlab jupyter:jupyterlab	from 4.0.0 before 4.5.7	NVD

References

References

https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-37w4-hwhx-4rc4	x-refsource-confirm, mitigation, vendor-advisory
https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.7	x-refsource-misc, patch, release-notes
https://jupyterhub.readthedocs.io/en/5.2.1/explanation/websecurity.html	x-refsource-misc, product
https://jupyterlab.readthedocs.io/en/latest/user/extensions.html#extension-manager-implementations	x-refsource-misc, product
https://access.redhat.com/errata/RHSA-2026:43038
https://access.redhat.com/errata/RHSA-2026:60520
https://access.redhat.com/security/cve/CVE-2026-42266
https://bugzilla.redhat.com/show_bug.cgi?id=2477072
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42266.json

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.