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CVE-2026-42266

37
FAUCET Score

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.

First published: May 13, 2026Last modified: Jun 30, 2026

Impacted Technologies

VendorProductVersion(s)CPE
>= 4.0.0, < 4.5.7CPE matchmatch criteria
cpe:2.3:a:jupyter:jupyterlab:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.8HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.55%
Probability of exploitation in next 30 days
EPSS Percentile
42.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0055 is in the 33rd percentile among its peer group of 17,829 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.3 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
pippatch availablevia ghsa
Product: jupyterlabFixed in: 4.5.7

Vendor Advisories (1)

pipGHSA-37w4-hwhx-4rc4high

JupyterLab has an Extension Manager API/GUI Policy Discrepancy, allowing 3rd party (malicious) extensions install via POST request

May 5, 2026

References

access.redhat.com / errata/RHSA-2026:43038
access.redhat.com / security/cve/CVE-2026-42266
bugzilla.redhat.com / show_bug.cgi
security.access.redhat.com / data/csaf/v2/vex/2026/cve-2026-42266.json
github.com / jupyterlab/jupyterlab/releases/tag/v4.5.7
PatchRelease Notes
github.com / jupyterlab/jupyterlab/security/advisories/GHSA-37w4-hwhx-4rc4
MitigationVendor Advisory
jupyterhub.readthedocs.io / en/5.2.1/explanation/websecurity.html
Product
jupyterlab.readthedocs.io / en/latest/user/extensions.html
Product