Jupyter JupyterLab up to 4.5.9/4.6.1 Notebook Extension index.ts code injection

Summaryinfo

A vulnerability marked as critical has been reported in Jupyter JupyterLab up to 4.5.9/4.6.1. Affected by this vulnerability is an unknown functionality of the file packages/notebook-extension/src/index.ts of the component Notebook Extension. The manipulation of the argument sideBySideLeftMarginOverride/sideBySideRightMarginOverride leads to code injection. This vulnerability is traded as CVE-2026-73417. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in Jupyter JupyterLab up to 4.5.9/4.6.1 and classified as critical. This issue affects an unknown code of the file packages/notebook-extension/src/index.ts of the component Notebook Extension. The manipulation of the argument sideBySideLeftMarginOverride/sideBySideRightMarginOverride with an unknown input leads to a code injection vulnerability. Using CWE to declare the problem leads to CWE-94. The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

jupyterlab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture. From 3.3.0 until 4.5.10 and 4.6.2, JupyterLab allows notebook settings to be shared and applied through an overrides.json file using the Import button in the Settings Editor. In packages/notebook-extension/schema/tracker.json and packages/notebook-extension/src/index.ts, the sideBySideLeftMarginOverride and sideBySideRightMarginOverride settings are not properly validated before being inserted into style content, allowing a crafted settings file to contain instructions that execute as code instead of only changing display preferences. A user can import the malicious file, or an attacker with access to a shared settings location can plant an overrides.json that is applied automatically. The embedded code runs with the affected user's access and can read or modify notebooks and files and run code through the notebook server, including on a connected kernel. This issue is fixed in versions 4.5.10 and 4.6.2.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-73417 since 08/12/2026. The exploitation is known to be easy. The attack may be initiated remotely. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1059 according to MITRE ATT&CK.

Upgrading to version 4.5.10 or 4.6.2 eliminates this vulnerability.

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Productinfo

Vendor

• Jupyter

Name

• JupyterLab

Version

• 4.5.0
• 4.5.1
• 4.5.2
• 4.5.3
• 4.5.4
• 4.5.5
• 4.5.6
• 4.5.7
• 4.5.8
• 4.5.9
• 4.6.0
• 4.6.1

CPE 2.3info

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CPE 2.2info

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