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GHSA-37w4-hwhx-4rc4

HighCVSS 8.8 / 10

Published May 5, 2026·Last modified May 21, 2026

Affected Components(0)

No affected components available

Description

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=readonly

or the following traitlet:

c.LabApp.extension_manager = 'readonly'

You can confirm that the read-only manager is in use from GUI:

Note: configuration of a PyPI proxy with allow-listed packages is not sufficient to protect from this vulnerability.

References

allow-list https://jupyterlab.readthedocs.io/en/stable/user/extensions.html#listing-configuration
https://jupyterhub.readthedocs.io/en/5.2.1/explanation/websecurity.html
https://jupyterlab.readthedocs.io/en/latest/user/extensions.html#extension-manager-implementations

Risk Scores

Base Score

8.8

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a high impact on the availability of the system.

Threat Intelligence

8.1

Exploitation activity has been observed. Apply available patches or mitigations urgently.

EPSS

0.55%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit

Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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High severity

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