CVE-2026-42557 HIGH

CVE-2026-42557: jupyterlab: Command linker attributes in HTML enable one-click command execution from untrusted content

Vendor Jupyterlab
Product jupyterlab
Weakness CWE-79 · XSS
Published May 13, 2026
Last update May 14, 2026

CVSS base score

8.6/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

May 13, 2026 CVE published
May 14, 2026 Record updated