How severe is CVE-2026-42266?

CVE-2026-42266 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-42266 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-42266?

CVE-2026-42266 affects Jupyter Jupyterlab. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-42266?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-42266 have an EU (EUVD) identifier?

Yes. CVE-2026-42266 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29995.

When was CVE-2026-42266 published?

CVE-2026-42266 was published on 2026-05-13 and last updated on 2026-07-06.

CVE-2026-42266

CVE-2026-42266 is a high-severity vulnerability in Jupyter Jupyterlab with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-88.

Key facts

Severity: High (CVSS 3.x base score 8.8)
EPSS exploit prediction: 1% (41st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-29995
Weakness: CWE-88
Affected product: Jupyter Jupyterlab
Published: 2026-05-13
Last modified: 2026-07-06

Description

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.

Frequently asked questions

What is CVE-2026-42266?: 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.
How severe is CVE-2026-42266?: CVE-2026-42266 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-42266 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-42266?: CVE-2026-42266 affects Jupyter Jupyterlab. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-42266?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-42266 have an EU (EUVD) identifier?: Yes. CVE-2026-42266 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29995.
When was CVE-2026-42266 published?: CVE-2026-42266 was published on 2026-05-13 and last updated on 2026-07-06.

References

Affected products (1)

cpe:2.3:a:jupyter:jupyterlab:*:*:*:*:*:*:*:*

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