CVE-2026-42266
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.63%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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 3.1
- 8.8 HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.63% probability · 48th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-88, CWE-602
- Affected
- jupyter/jupyterlab
- Source
- security-advisories@github.com
References
- https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.7Patch, Release Notes
- https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-37w4-hwhx-4rc4Mitigation, Vendor Advisory
- https://jupyterhub.readthedocs.io/en/5.2.1/explanation/websecurity.htmlProduct
- https://jupyterlab.readthedocs.io/en/latest/user/extensions.html#extension-manager-implementationsProduct
- 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
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.