JupyterLab has an Extension Manager API/GUI Policy Discrepancy, allowing 3rd party (malicious) extensions install via POST request
The allow-list of extensions that can be installed from PyPI Extension Manager (allowed_extensions_uris) is not correctly enforced by JupyterLab prior to 4.5.7. The PyPI Extension Manager was not contained to packages listed on the default PyPI index.
This has security implications for deployments that:
- have allow-listed specific extensions with aim to prevent users from installing packages
- have the kernel and terminals disabled or delegated to remote hosts (thus no access to install packages in the single-user server environment)
- have multi-tenant deployments that is not configured for untrusted users (as per documented on JupyterHub https://jupyterhub.readthedocs.io/en/5.2.1/explanation/websecurity.html)
- have the (default) PyPI Extension Manager enabled
Impact
An authenticated attacker - such as a student in a shared JupyterHub environment or a user in a multi-tenant JupyterLab deployment - can escalate their privileges. This might allow for data exfiltration, lateral movement within the network, and persistent compromise of the server infrastructure.
Patches
JupyterLab v4.5.7 contains the patch.
Users of applications that depend on JupyterLab, such as Notebook v7+, should update jupyterlab package too.
Workarounds
Switch to read-only extension manager by adding the following command line option:
--LabApp.extension_manager=readonlyor the following traitlet:
c.LabApp.extension_manager = 'readonly'You can confirm that the read-only manager is in use from GUI:
<img width="293" height="293" alt="image" src="https://github.com/user-attachments/assets/8016c809-633e-4ed0-a5bc-6bc4793caa0f" />Note: configuration of a PyPI proxy with allow-listed packages is not sufficient to protect from this vulnerability.
References
Software afectado
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| Plataforma | Paquete | Versiones vulnerables | Corregida en |
|---|---|---|---|
| Python (PyPI) | jupyterlab | >= 4.0.0, < 4.5.7 | 4.5.7 |
Referencias
- https://jupyterhub.readthedocs.io/en/5.2.1/explanation/websecurity.html
- https://jupyterlab.readthedocs.io/en/latest/user/extensions.html#extension-manager-implementations
- https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-37w4-hwhx-4rc4
- https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.7
- https://nvd.nist.gov/vuln/detail/CVE-2026-42266
- https://github.com/jupyterlab/jupyterlab
- https://github.com/pypa/advisory-database/tree/main/vulns/jupyterlab/PYSEC-2026-164.yaml
- Vector CVSS
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H- Debilidad (CWE)
CWE-20, CWE-602, CWE-88- Plataforma
- Python (PyPI)
- Paquete
jupyterlab- Publicada
- 05.05.2026
- Actualizado
- 11.10.2026 15:17
Fuentes y licencias
OSV / GitHub Advisory Database - PYSEC-2026-164 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-37w4-hwhx-4rc4 - CC BY 4.0
Historial de vulnerabilidades: jupyterlab
Todas las vulnerabilidades publicadas de este paquete (Python (PyPI)), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.
- Entradas en total
- 19
- Primera → última
- 08.2021 10.2026
- Sin corrección
- 0
- Explotada en ataques
- 0
Distribución por gravedad
- Crítica 1
- Alta 8
- Media 8
- Baja 2
Divulgaciones por año
- 2021: 1
- 2022: 0
- 2023: 0
- 2024: 4
- 2025: 1
- 2026: 13
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JupyterLab has an Extension Manager API/GUI Policy Discrepancy, allowing 3rd party (malicious) extensions install via POST request esta entrada
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