CVE-2026-42557
jupyterlab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture.
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | jupyterlab | <= 4.5.6 | 4.5.7 |
| pip | notebook | >= 7.0.0, <= 7.5.5 | 7.5.6 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Jupyter | Jupyterlab | before 4.5.7 |
| Jupyter | Notebook | from 7.0.0 before 7.5.6 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-mqcg-5x36-vfcg
- https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-mqcg-5x36-vfcg
- https://jupyterlab.readthedocs.io/en/latest/user/commands.html#commands-in-markdown-files
- https://nvd.nist.gov/vuln/detail/CVE-2026-42557
- https://access.redhat.com/errata/RHSA-2026:43038
- https://access.redhat.com/errata/RHSA-2026:60520
- https://access.redhat.com/security/cve/CVE-2026-42557
- https://bugzilla.redhat.com/show_bug.cgi?id=2477086
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42557.json