# CVE-2026-40171: jupyterlab: In Jupyter Notebook versions 7.0.0 through 7.5.5, JupyterLab versions 4.5.6 and earlier, and the corresponding @jupyt...

CVE-2026-40171 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-40171, released May 6, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-40171
- Priority: Routine
- CVSS: n/a
- EPSS: 0.0048
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 6, 2026

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | jupyter-notebook Debian 14 | 7.4.7-3 | [DEBIAN-CVE-2026-40171](https://patchblox.com/security/data/fix/linux/debian-cve-2026-40171.md) | May 6, 2026 |
| Linux | jupyterlab Debian 14 | 4.4.10+ds1+~3.1.0+~0.16.6+~cs1.4.4-3 | [DEBIAN-CVE-2026-40171](https://patchblox.com/security/data/fix/linux/debian-cve-2026-40171.md) | May 6, 2026 |

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Data as of 2026-11-08T00:53:09Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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