JupyterLab has an Extension Manager API/GUI Policy Discrepancy allowing 3rd party (malicious) extensions install via POST request.
Summary
| CVE | CVE-2026-42266 |
|---|---|
| State | PUBLISHED |
| Assigner | GitHub_M |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-05-13 16:16:47 UTC |
| Updated | 2026-07-06 13:16:54 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 8.8 HIGH from ADP
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS: 0.005300000 probability, percentile 0.409410000 (date 2026-07-08)
Problem Types: CWE-88 | CWE-602 | CWE-88 CWE-88: Improper Neutralization of Argument Delimiters in a Command ('Argument Injection') | CWE-602 CWE-602: Client-Side Enforcement of Server-Side Security | CWE-88 Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | ADP | CVSS | 8.8 | HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | [email protected] | Secondary | 8.8 | HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | Secondary | 8.8 | HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | CNA | DECLARED | 8.8 | HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Application | Jupyter | Jupyterlab | All | All | All | All |
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Jupyterlab | Jupyterlab | affected >= 4.0.0, < 4.5.7 | Not specified |
| ADP | Red Hat | Migration Toolkit For Applications 8 | Not specified | Not specified |
| ADP | Red Hat | Red Hat OpenShift AI RHOAI | Not specified | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42266.json | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | security.access.redhat.com | |
| bugzilla.redhat.com/show_bug.cgi | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | bugzilla.redhat.com | |
| jupyterhub.readthedocs.io/en/5.2.1/explanation/websecurity.html | [email protected] | jupyterhub.readthedocs.io | Product |
| access.redhat.com/security/cve/CVE-2026-42266 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| github.com/jupyterlab/jupyterlab/releases/tag/v4.5.7 | [email protected] | github.com | Patch, Release Notes |
| jupyterlab.readthedocs.io/en/latest/user/extensions.html | [email protected] | jupyterlab.readthedocs.io | Product |
| github.com/jupyterlab/jupyterlab/security/advisories/GHSA-37w4-hwhx-4rc4 | [email protected] | github.com | Mitigation, Vendor Advisory |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| ADP | 2026-05-13T16:02:13.807Z | Reported to Red Hat. |
| ADP | 2026-05-13T15:08:49.846Z | Made public. |
Workarounds
ADP: Upgrade JupyterLab to version 4.5.7 or later. Set the JupyterLab extension manager to read-only mode to prevent users from installing unauthorized extensions. Note: configuring a PyPI proxy with an allow list of packages is not sufficient to protect against this vulnerability.