JupyterLab has an Extension Manager API/GUI Policy Discrepancy, allowing 3rd party (malicious) extensions install via POST request

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

• CISA KEV Not listed.
• EPSS 0.057, the 92nd percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

1. 31 Oct 2026, 14:11 UTC First seen by agentprime
2. 31 Oct 2026, 14:11 UTC Confirmed by OSV

Sources

• GitHub Advisory Database: GHSA-37w4-hwhx-4rc4
• OSV: GHSA-37w4-hwhx-4rc4
• github.com/jupyterlab/jupyterlab/security/advisories/GHSA-37w4-hwhx-4rc4
• nvd.nist.gov/vuln/detail/CVE-2026-42266
• github.com/jupyterlab/jupyterlab
• github.com/jupyterlab/jupyterlab/releases/tag/v4.5.7
• github.com/pypa/advisory-database/tree/main/vulns/jupyterlab/PYSEC-2026-164.yaml
• jupyterhub.readthedocs.io/en/5.2.1/explanation/websecurity.html
• jupyterlab.readthedocs.io/en/latest/user/extensions.html#extension-manager-implementations

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.