Vulnerability · Published May 13, 2026 · Assigned by GitHub_M
CVE-2026-42557jupyterlab: Command linker attributes in HTML enable one-click command execution from untrusted content
High 8.8
In plain English
A high-severity cross-site scripting in notebook from jupyter. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 42% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.24 | jupyter-notebook | 7.5.6-r0 | ALPINE-CVE-2026-42557 |
| Debian:13 | jupyterlab | no fix listed | DEBIAN-CVE-2026-42557 |
| Debian:14 | jupyterlab | 4.4.10+ds1+~3.1.0+~0.16.6+~cs1.4.4-3 | DEBIAN-CVE-2026-42557 |
| PyPI | jupyterlab | 4.5.7 | GHSA-mqcg-5x36-vfcg |
| PyPI | jupyterlab | 4.5.7 | PYSEC-2026-2537 |
| PyPI | notebook | 7.5.6 | GHSA-mqcg-5x36-vfcg |
| PyPI | notebook | 7.5.6 | PYSEC-2026-2681 |
| Ubuntu:25.10 | jupyterlab | no fix listed | UBUNTU-CVE-2026-42557 |
| Ubuntu:26.04:LTS | jupyterlab | no fix listed | UBUNTU-CVE-2026-42557 |
| Ubuntu:26.10 | jupyterlab | no fix listed | UBUNTU-CVE-2026-42557 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| jupyterlab | jupyterlab | < 4.5.7 |
| jupyter | notebook | >= 7.0.0, < 7.5.6 |
Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
References
- https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-mqcg-5x36-vfcg x_refsource_CONFIRM
- https://access.redhat.com/security/cve/CVE-2026-42557 vdb-entry, x_refsource_REDHAT
- RHBZ#2477086 issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42557.json x_sadp-csaf-vex
- https://access.redhat.com/errata/RHSA-2026:43038 vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:60520 vendor-advisory, x_refsource_REDHAT