# CVE-2026-42557: jupyterlab: jupyterlab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Arc...

CVE-2026-42557 is fixed in jupyterlab on 1 platform by DEBIAN-CVE-2026-42557 (version 4.4.10+ds1+~3.1.0+~0.16.6+~cs1.4.4-3), released May 13, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2026-42557
- Priority: Urgent
- CVSS: 9.6 (critical)
- EPSS: 0.0049
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 13, 2026

## Description

jupyterlab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture. Prior to 4.5.7, JupyterLab's HTML sanitizer allowlists data-commandlinker-command and data-commandlinker-args on button elements, while CommandLinker listens for all click events on document.body and executes the named command without checking whether the element came from trusted JupyterLab UI. A notebook with a pre-saved HTML cell output containing a deceptive button can trigger arbitrary JupyterLab commands - including arbitrary code execution - on a single user click, without any code being submitted for execution by the user. This vulnerability is fixed in 4.5.7.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | jupyterlab Debian 14 | 4.4.10+ds1+~3.1.0+~0.16.6+~cs1.4.4-3 | [DEBIAN-CVE-2026-42557](https://patchblox.com/security/data/fix/linux/debian-cve-2026-42557.md) | May 13, 2026 |

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Data as of 2026-11-08T19:12:23Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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