High severity · published May 13, 2026
CVE-2026-42266
JupyterLab has an Extension Manager API/GUI Policy Discrepancy allowing 3rd party (malicious) extensions install via POST request.
8.8
CVSS
5.7%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)5.7% · higher than 93% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
JU
jupyterlab · jupyterlab
>= 4.0.0, < 4.5.7 · source: vendor, NVD
RH
Red Hat Migration Toolkit for Applications 8.2 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat OpenShift AI (RHOAI) · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat OpenShift AI 3.4 · Red Hat
All versions, or not specified · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-42266
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-42266
Patch
https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.7
Mitigation
https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-37w4-hwhx-4rc4
Product
https://jupyterhub.readthedocs.io/en/5.2.1/explanation/websecurity.html
Product
https://jupyterlab.readthedocs.io/en/latest/user/extensions.html#extension-manager-implementations
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:43038
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:60520
More from jupyterlab
9.6
CVE-2026-42557
jupyterlab: Command linker attributes in HTML enable one-click command execution from untrusted content
8.6
CVE-2026-73417
JupyterLab: Cross-site scripting (XSS) via crafted settings file (`overrides.json`)
8.4
CVE-2026-40171
Jupyter Notebook and JupyterLab token theft via stored XSS in help command linker
8.1
CVE-2026-102831
JupyterLab: Cross-site scripting (XSS) in JupyterLab via notebook cells pasted from the system clipboard
7.5
CVE-2026-73626
JupyterLab before 4.6.2 Authentication Bypass via PyPIExtensionManager