CVE-2026-42266

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

HIGH
8.8
CVSS Score
Published: May 13, 2026 at 03:08 PM UTC
Updated: August 28, 2026 at 04:32 PM UTC
3 products affected across 3 vendorsJupyterlabOpenShift AIJupyterlab

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Severity
HIGH8.8
Exploit prediction
EPSS 6%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

4.0.0 ≤ v < 4.5.7
Affected range stops below 4.5.7, so it looks safe — our inference, not a vendor statement
v < 4.5.7
Affected range stops below 4.5.7, so it looks safe — our inference, not a vendor statement
All versions
Vendor states this is fixed in 1787073546 (unaffected)
Vendor states this is fixed in 1787073593 (unaffected)
Vendor states this is fixed in 1787073605 (unaffected)
Vendor states this is fixed in 1787073713 (unaffected)
Vendor states this is fixed in 1787073717 (unaffected)
Vendor states this is fixed in 1787073913 (unaffected)
Vendor states this is fixed in 1787073929 (unaffected)
Vendor states this is fixed in 1787074078 (unaffected)
Vendor states this is fixed in 1787074331 (unaffected)
Vendor states this is fixed in 1787076481 (unaffected)
Vendor states this is fixed in 1787076778 (unaffected)
Vendor states this is fixed in 1787077779 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (9)

x_refsource_CONFIRMMitigationVendor Advisory
Source: cverecord
https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-37w4-hwhx-4rc4
x_refsource_MISCPatchRelease Notes
Source: cverecord
https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.7
Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://access.redhat.com/security/cve/CVE-2026-42266
Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://bugzilla.redhat.com/show_bug.cgi?id=2477072
Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://access.redhat.com/errata/RHSA-2026:43038

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.8HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-88CWE-602

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