CVE-2026-42557
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
Debian Affected 3 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Affected | — |
| sid | Affected | — |
| forky | Affected | — |
Package impact
| Ecosystem | Package | Vulnerable | Fixed |
|---|---|---|---|
| PyPI | jupyterlab | <4.5.7 | 4.5.7 |
| PyPI | notebook | >=7.0.0,<7.5.6 | 7.5.6 |
| PIP | notebook | >= 7.0.0, <= 7.5.5 | 7.5.6 |
| PIP | jupyterlab | <= 4.5.6 | 4.5.7 |
Application impact
| Vendor | Product | Versions | Fixed |
|---|---|---|---|
| jupyter | jupyterlab | {"endExcluding":"4.5.7"} | 4.5.7 |
| jupyter | notebook | {"startIncluding":"7.0.0","endExcluding":"7.5.6"} | 7.5.6 |
References
- https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-mqcg-5x36-vfcg
- https://nvd.nist.gov/vuln/detail/CVE-2026-42557
- https://github.com/jupyterlab/jupyterlab
- https://jupyterlab.readthedocs.io/en/latest/user/commands.html#commands-in-markdown-files
- https://security-tracker.debian.org/tracker/CVE-2026-42557
- https://github.com/advisories/GHSA-mqcg-5x36-vfcg
CWEs
CWE-79
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.