CVE-2026-73416

Received Received - Intake

PyPI Extension Bypass in JupyterLab

Publication date: 2026-08-13

Last updated on: 2026-08-13

Assigner: GitHub, Inc.

Description

jupyterlab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture. From 4.5.0 until 4.5.10 and 4.6.2, in jupyterlab/extensions/manager.py and jupyterlab/extensions/pypi.py, JupyterLab's PyPI extension manager enforces blocked_extensions_uris by comparing requested install names to blocklist entries with custom normalization that is weaker than PyPI package-name canonicalization. An authenticated user can request a PyPI-equivalent spelling such as JupyterLab.Git for a blocklisted package such as jupyterlab-git, and JupyterLab accepts the install request even though pip resolves the variant to the same package. Security impact requires an allowlist or blocklist intended to restrict package installation, the PyPI Extension Manager, and kernels and terminals that are disabled or delegated to remote hosts. The bypass lets an authenticated user install a prohibited extension, defeat integrity restrictions, and affect availability without gaining new read access. This issue is fixed in versions 4.5.10 and 4.6.2.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-13

Last Modified

2026-08-13

Generated

2026-08-14

AI Q&A

2026-08-14

EPSS Evaluated

N/A

NVD

CVE-2026-73416

Affected Vendors & Products

Vendor	Product	Version / Range
jupyterlab	jupyterlab	to 4.5.10 (inc)
jupyterlab	jupyterlab	4.6.2

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-180	The product validates input before it is canonicalized, which prevents the product from detecting data that becomes invalid after the canonicalization step.
CWE-178	The product does not properly account for differences in case sensitivity when accessing or determining the properties of a resource, leading to inconsistent results.

Attack-Flow Graph

Executive Summary

This vulnerability in JupyterLab allows an authenticated user to bypass package installation restrictions by using alternative spellings of blocked package names. The PyPI extension manager's normalization process is weaker than PyPI's canonicalization, enabling installation of prohibited extensions.

Impact Analysis

An attacker could install unauthorized extensions, bypassing intended security controls. This could lead to compromised system integrity, reduced availability, or unintended functionality without gaining additional read access.

Compliance Impact

This vulnerability could violate compliance requirements that mandate strict control over installed software, such as preventing unauthorized extensions that may introduce data access or processing risks. Organizations relying on blocklists for compliance may find their controls ineffective.

Mitigation Strategies

Upgrade JupyterLab to version 4.5.10 or 4.6.2 or later to address the vulnerability in the PyPI extension manager.

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