CVE-2026-40171
Jupyter Notebook and JupyterLab token theft via stored XSS in help command linker
Description
In Jupyter Notebook versions 7.0.0 through 7.5.5, JupyterLab versions 4.5.6 and earlier, and the corresponding @jupyter-notebook/help-extension and @jupyterlab/help-extension packages before 7.5.6 and 4.5.7, a stored cross-site scripting issue in the help command linker can be chained with attacker-controlled notebook content to steal authentication tokens with a single click. An attacker can craft a malicious notebook file containing elements that appear indistinguishable from legitimate controls and trigger execution when a user interacts with them. Successful exploitation allows theft of the user's authentication token and complete takeover of the Jupyter session through the REST API, including reading files, creating or modifying files, accessing kernels to execute arbitrary code, and creating terminals for shell access. This issue has been fixed in Notebook 7.5.6, JupyterLab 4.5.7, @jupyter-notebook/help-extension 7.5.6, and @jupyterlab/help-extension 4.5.7. As a workaround, disable the affected help extensions or set allowCommandLinker to false in the sanitizer configuration.
INFO
Published Date :
May 6, 2026, 8:16 p.m.
Last Modified :
Oct. 26, 2026, 7:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update Jupyter Notebook to 7.5.6 or later.
- Update JupyterLab to 4.5.7 or later.
- Disable help extensions or set allowCommandLinker to false.
- Apply updates for @jupyter-notebook/help-extension and @jupyterlab/help-extension.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-40171.
| URL | Resource |
|---|---|
| https://github.com/jupyter/notebook/security/advisories/GHSA-rch3-82jr-f9w9 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-40171 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-40171
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-40171 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-40171 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Translated by [email protected]
Oct. 26, 2026
Action Type Old Value New Value Added Translation Title: notebook, help-extension y jupyterlab de jupyter, Description: En las versiones de Jupyter Notebook 7.0.0 a 7.5.5, las versiones de JupyterLab 4.5.6 y anteriores, y los paquetes correspondientes @jupyter-notebook/help-extension y @jupyterlab/help-extension anteriores a 7.5.6 y 4.5.7, un problema de cross-site scripting almacenado en el enlazador de comandos de ayuda puede encadenarse con contenido de notebook controlado por el atacante para robar tokens de autenticación con un solo clic. Un atacante puede crear un archivo de notebook malicioso que contenga elementos que parezcan indistinguibles de los controles legítimos y activar la ejecución cuando un usuario interactúa con ellos. La explotación exitosa permite el robo del token de autenticación del usuario y la toma de control completa de la sesión de Jupyter a través de la API REST, incluyendo la lectura de archivos, la creación o modificación de archivos, el acceso a kernels para ejecutar código arbitrario y la creación de terminales para acceso a la shell. Este problema ha sido solucionado en Notebook 7.5.6, JupyterLab 4.5.7, @jupyter-notebook/help-extension 7.5.6 y @jupyterlab/help-extension 4.5.7. Como solución alternativa, deshabilite las extensiones de ayuda afectadas o establezca allowCommandLinker en false en la configuración del saneador. -
CVE Modified by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'jupyter', 'product': 'notebook', 'versions': [{'status': 'affected', 'version': '>=7.0.0, <= 7.5.5'}]}, {'vendor': 'jupyterlab', 'product': 'help-extension', 'versions': [{'status': 'affected', 'version': '<=4.5.6'}]}, {'vendor': 'jupyterlab', 'product': 'jupyterlab', 'versions': [{'status': 'affected', 'version': '<= 4.5.6'}]}, {'vendor': 'jupyter-notebook', 'product': 'help-extension', 'versions': [{'status': 'affected', 'version': '>=7.0.0,<= 7.5.5'}]}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-40171', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-05-07T00:00:00+00:00'} -
New CVE Received by [email protected]
May. 06, 2026
Action Type Old Value New Value Added Description In Jupyter Notebook versions 7.0.0 through 7.5.5, JupyterLab versions 4.5.6 and earlier, and the corresponding @jupyter-notebook/help-extension and @jupyterlab/help-extension packages before 7.5.6 and 4.5.7, a stored cross-site scripting issue in the help command linker can be chained with attacker-controlled notebook content to steal authentication tokens with a single click. An attacker can craft a malicious notebook file containing elements that appear indistinguishable from legitimate controls and trigger execution when a user interacts with them. Successful exploitation allows theft of the user's authentication token and complete takeover of the Jupyter session through the REST API, including reading files, creating or modifying files, accessing kernels to execute arbitrary code, and creating terminals for shell access. This issue has been fixed in Notebook 7.5.6, JupyterLab 4.5.7, @jupyter-notebook/help-extension 7.5.6, and @jupyterlab/help-extension 4.5.7. As a workaround, disable the affected help extensions or set allowCommandLinker to false in the sanitizer configuration. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:H/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-79 Added Reference https://github.com/jupyter/notebook/security/advisories/GHSA-rch3-82jr-f9w9