CVE-2026-42266
JupyterLab has an Extension Manager API/GUI Policy Discrepancy, allowing 3rd party (malicious) extensions install via POST request
8.8
HIGH
CVSS 3.1
EPSS 0.03%
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.
How to fix CVE-2026-42266
To remediate CVE-2026-42266, upgrade the affected package to a fixed version below.
- —upgrade to 4.5.7 or later
- —no fix listed
- —upgrade to 4.5.7 or later
- —upgrade to 4.5.7 or later
Is CVE-2026-42266 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (4)
- >= 4.0.0, < 4.5.7
- from 0
- >= 4.0.0, < 4.5.7
- >= 4.0.0, < 4.5.7
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH8.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |