CVE-2026-102831

Awaiting Analysis Awaiting Analysis - Queue

Clipboard Cell-Paste XSS in JupyterLab

Publication date: 2026-09-29

Last updated on: 2026-10-02

Assigner: GitHub, Inc.

Description

JupyterLab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture. From JupyterLab 4.5.0 until 4.5.11 and 4.6.4, from Notebook 7.5.0 until 7.6.3, and from JupyterLite Core 0.7.0 until 0.8.4, the system clipboard cell-paste path accepts attacker-controlled cell JSON without clearing metadata.trusted. When useSystemClipboardForCells is active and pasteCodeCellsWithoutOutput is disabled, a pasted code cell can mark HTML output as trusted, bypass output sanitization, and execute script in the authenticated JupyterLab origin without executing the cell. Markdown and raw cells are not affected because their output is sanitized. This issue is fixed in JupyterLab 4.5.11 and 4.6.4, Notebook 7.6.3, and JupyterLite Core 0.8.4.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-09-29

Last Modified

2026-10-02

Generated

2026-10-19

AI Q&A

2026-09-30

EPSS Evaluated

2026-10-18

NVD

CVE-2026-102831

EUVD

EUVD-2026-89338

Affected Vendors & Products

Vendor	Product	Version / Range
jupyterlab	jupyterlab	From 4.5.0 (inc) to 4.5.11 (inc)
jupyterlab	jupyterlab	From 4.6.4 (inc)
notebook	notebook	From 7.5.0 (inc) to 7.6.3 (inc)
jupyterlite	jupyterlite_core	From 0.7.0 (inc) to 0.8.4 (inc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-79	The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
CWE-345	The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.

Attack-Flow Graph

Executive Summary

This vulnerability is a cross-site scripting (XSS) flaw in JupyterLab versions 4.5.0 through 4.6.3 and related applications like Notebook 7.5+. When users paste notebook cells from the system clipboard into JupyterLab, the paste functionality parses clipboard text as cell JSON without clearing the metadata.trusted flag. This allows an attacker to include malicious JavaScript in the clipboard, which executes when pasted if the metadata.trusted flag is set to true. The script runs in the same origin as the authenticated user, enabling it to interact with the Jupyter Server REST API, read or write files, start kernels, and execute code without requiring user interaction beyond pasting.

Detection Guidance

This vulnerability can be detected by checking the installed versions of JupyterLab, Notebook, and JupyterLite Core. Run commands like 'jupyter lab --version', 'jupyter notebook --version', and 'pip show jupyterlite-core' to identify affected versions. Affected versions are JupyterLab 4.5.0 to 4.5.11 and 4.6.0 to 4.6.3, Notebook 7.5.0 to 7.6.2, and JupyterLite Core 0.7.0 to 0.8.3.

Impact Analysis

This vulnerability allows an attacker to execute arbitrary code in your JupyterLab environment by tricking you into pasting malicious clipboard content. The attacker could read or write files, start kernels, interact with the Jupyter Server REST API, and perform actions on your behalf without needing further user interaction. This could lead to data theft, unauthorized code execution, or system compromise.

Compliance Impact

This vulnerability could potentially violate compliance with GDPR and HIPAA by enabling unauthorized code execution through clipboard manipulation. An attacker could execute malicious scripts in the authenticated JupyterLab origin, allowing access to sensitive data or system functions without proper authorization. This undermines data integrity and confidentiality requirements in these regulations.

Mitigation Strategies

Upgrade JupyterLab to version 4.5.11 or 4.6.4, Notebook to 7.6.3, and JupyterLite Core to 0.8.4 or later.
Disable the useSystemClipboardForCells setting if enabled, as this reduces exposure to the vulnerability.
Avoid pasting cells from the system clipboard until the system is upgraded.
Monitor for unusual activity or unauthorized code execution in JupyterLab sessions.

Hi! I’m here to help you understand CVE-2026-102831. Ask me anything about the vulnerability, its impact, or mitigation strategies.

0/70