CVE-2026-42266

Summary

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.

Affected Software

Weaknesses

• 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

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: no
  • Technical Impact: total

jupyterlab: JupyterLab: Arbitrary code execution due to improper enforcement of extension allow-list

Additional References

• https://access.redhat.com/security/cve/CVE-2026-42266
• https://bugzilla.redhat.com/show_bug.cgi?id=2477072
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42266.json

References

• https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-37w4-hwhx-4rc4
• https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.7
• https://jupyterhub.readthedocs.io/en/5.2.1/explanation/websecurity.html
• https://jupyterlab.readthedocs.io/en/latest/user/extensions.html#extension-manager-implementations

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