CVE-2026-42557
CriticalCVSS 9.6Exploitation Probability (EPSS)
Low risk31th percentile - higher than 31% of all known CVEs
Summary
JupyterLab prior to 4.5.7 allows data-commandlinker-command and data-commandlinker-args attributes on button elements in its HTML sanitizer. CommandLinker executes commands on click without verifying the element's origin, enabling arbitrary command execution via a crafted notebook cell.
Risk Assessment
High risk for the organization – an attacker can exploit this to execute arbitrary code in the context of the JupyterLab user, potentially leading to data theft or session takeover.
Recommendation
Update JupyterLab to version 4.5.7 or later. Advise users about the risks of opening notebooks from untrusted sources.
Original NVD description (English source)
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.