Cyber Resilience

CVE-2026-42266

Jupyterlab 4.0.0 – 4.5.7

Published
13 May 2026
Modified
22 July 2026
Patch / advisory
View advisory
CVSS Score v3.1 8.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0055 43th percentile
Risk Priority 64 floored blend · peak EPSS

Summary

CVE-2026-42266 is a high-severity Argument Injection (CWE-88) vulnerability in Jupyter Jupyterlab. Its CVSS base score is 8.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Command and Scripting Interpreter (T1059); ranked at the 43th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to AC-25 (Reference Monitor) and AC-3 (Access Enforcement) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A05:2025 InjectionA06:2025 Insecure Design

EU & UK References

Vulnerability Data

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…

more

PyPI Extension Manager was not contained to packages listed on the default PyPI index. This vulnerability is fixed in 4.5.7.

CWE(s)
CWE-88CWE-602

Related Threats

MITRE ATT&CK Enterprise Techniques

T1059 Command and Scripting Interpreter Execution
Adversaries may abuse command and script interpreters to execute commands, scripts, or binaries.
attack.mitre.org →
T1059.001 PowerShell Execution
Adversaries may abuse PowerShell commands and scripts for execution.
attack.mitre.org →
T1059.003 Windows Command Shell Execution
Adversaries may abuse the Windows command shell for execution.
attack.mitre.org →
T1059.004 Unix Shell Execution
Adversaries may abuse Unix shell commands and scripts for execution.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-39700Same product: Jupyter Jupyterlab
CVE-2025-59842Same product: Jupyter Jupyterlab
CVE-2026-42557Same product: Jupyter Jupyterlab
CVE-2024-43805Same product: Jupyter Jupyterlab
CVE-2026-44182Same vendor: Jupyter
CVE-2026-40110Same vendor: Jupyter
CVE-2024-35225Same vendor: Jupyter
CVE-2026-40864Same vendor: Jupyter
CVE-2026-35397Same vendor: Jupyter
CVE-2026-5422Same vendor: Jupyter

Affected Assets

jupyter
jupyterlab
4.0.0 — 4.5.7

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V10.7.1
  • V2.2.2
  • V8.3.1
  • V10.4.1

Mitigating Controls (NIST 800-53 r5) AI

AC-25 Reference Monitor good match

Requires a tamper-proof, always-invoked reference monitor that cannot be bypassed by client-side logic.

AC-3 Access Enforcement good match

Enforces all access decisions on the server according to policy rather than trusting client-supplied enforcement.

AC-4 Information Flow Enforcement good match

Enforces information-flow rules at the server boundary instead of delegating them to the client.

SA-11 Developer Testing and Evaluation good match

Developer testing can discover argument-injection flaws in command-construction code but does not stop their introduction.

SI-10 Information Input Validation good match

Input validation directly stops construction of command strings containing unneutralized delimiters or injected arguments.

SC-7 Boundary Protection partial match

Monitors and controls all external and key internal interfaces so that server-side policy cannot be off-loaded to clients.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require proper input validation and command construction to prevent argument injection.

PR.AA-05 partial match
prevents

Proper policy-based enforcement of authorizations implies server-side controls rather than client-only checks.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.27 Secure system architecture and engineering principles mostly match
prevents

Secure architecture principles discourage client-side trust but do not directly address this weakness.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect argument injection but does not prevent it at the source.

A.8.3 Information access restriction mostly match
prevents

Information access restriction is undermined when the client is trusted to enforce it.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle mandates input validation and command construction practices that directly prevent argument injection.

A.8.26 Application security requirements partial match
prevents

Application security requirements include explicit rules for safe command-line argument handling and escaping.

A.8.28 Secure coding partial match
prevents

Secure coding standards explicitly require proper neutralization of command arguments, directly eliminating CWE-88.

References