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.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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. (CVE-2026-40171)

Note that Nessus relies on the presence of the package as reported by the vendor.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - 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. (CVE-2026-40171)

ID	Name	Product	Family	Severity
313260	Linux Distros Unpatched Vulnerability : CVE-2026-40171	Nessus	Misc.	high
441037	SCA: security update for @jupyter-notebook/help-extension, @jupyterlab/help-extension, jupyterlab, notebook (GHSA-rch3-82jr-f9w9)	Tenable Cloud Security	SCA Checks	high
441037	SCA: security update for @jupyter-notebook/help-extension, @jupyterlab/help-extension, jupyterlab, notebook (GHSA-rch3-82jr-f9w9)	Tenable Self-Hosted Container Security	SCA Checks	high

Detections

Analytics

CVE-2026-40171

high

Tenable Plugins

high

high

high