PT-2026-67369 — Improper Access Control in Pypi Jupyterlab

PT-2026-67369 · Pypi · Jupyterlab

Published

2026-07-22

Updated

2026-07-22

CVSS v3.1

0.0

None

Vector

AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:N

The extension allowlist/blocklist check inside PyPIExtensionManager.install() was not enforced due to a missing await. For purposes of JupyterLab this was a secondary defense-in-depth check: install() was intended to enforce the allowlist/blocklist itself for any future uses and users calling this method directly (in addition to the separate check handling requests arriving through the HTTP API). The only runtime symptom was a RuntimeWarning: coroutine 'is install allowed' was never awaited.

This has security implications only for deployments that combine all of the following:

a custom extension or downstream integration that imports PyPIExtensionManager and calls install() directly with a package name influenced by untrusted user input (the stock JupyterLab HTTP handler is not affected - it performs its own awaited allowlist check before calling install());
an allowlist/blocklist configured with the intent of restricting which packages users can install;
the (default) PyPI Extension Manager enabled; and
kernels and terminals disabled or delegated to remote hosts, so that the custom extension's install() call is the only available package-install vector (otherwise a user with kernel access can install packages directly regardless of this check)

Impact

Low. No exposure for stock JupyterLab: the HTTP API and Extension Manager UI enforce the listing through a separate, correctly awaited check. The gap affected only custom extensions or downstream integrations that called the public install() method directly and relied on it to self-enforce.

Patches

JupyterLab v4.6.2 and v4.5.10 contain the patch.

Users of applications that depend on JupyterLab, such as Notebook v7+, should update jupyterlab package too.

Workarounds

No action is required for deployments that only expose extension management through the JupyterLab HTTP API / Extension Manager UI, as that path was already enforcing the listing via the handler's own check. Deployments wanting to disable programmatic extension installation entirely can switch to the read-only extension manager:

bash

--LabApp.extension manager=readonly

or the following traitlet:

python

c.LabApp.extension manager = 'readonly'

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

Fix

Improper Access Control

Found an issue in the description? Have something to add? Feel free to write us 👾

dbugs@ptsecurity.com

Weakness Enumeration

CWE-636CWE-284

Related Identifiers

GHSA-WHVH-WF3X-G77J

Affected Products

Jupyterlab