CVE-2026-102831 JupyterLab: Cross-site scripting (XSS) in JupyterLab via notebook cells pasted from the system clipboard
Attackers can execute arbitrary scripts in JupyterLab by pasting malicious cells, bypassing output sanitization when specific clipboard settings are enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-102831?
CVE-2026-102831 is a high-severity cross-site scripting vulnerability in jupyterlab, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Which versions are affected by CVE-2026-102831?
14 open source packages ship an affected version, including jupyterlab, jupyterlite and jupyterlite-core.
| Package | Affected | Fixed in |
|---|---|---|
jupyterlab PyPI | From 4.5.0 | 4.5.11, 4.6.4 |
jupyterlab PyPI | From 4.5.0 | 4.5.11 |
jupyterlab PyPI | From 4.5.0 | 4.5.11 |
jupyterlab PyPI | From 4.6.0 | 4.6.4 |
jupyterlab PyPI | From 4.6.0 | 4.6.4 |
jupyterlite PyPI | From 0.7.0 | 0.8.4 |
8 more packages
jupyterlite PyPI | From 0.7.0 | 0.8.4 |
jupyterlite PyPI | From 0.7.0 | 0.8.4 |
jupyterlite-core PyPI | From 0.7.0 | 0.8.4 |
jupyterlite-core PyPI | From 0.7.0 | 0.8.4 |
jupyterlite-core PyPI | From 0.7.0 | 0.8.4 |
notebook PyPI | From 7.5.0 | 7.6.3 |
notebook PyPI | From 7.5.0 | 7.6.3 |
notebook PyPI | From 7.5.0 | 7.6.3 |
How do I fix CVE-2026-102831?
Upgrade jupyterlab to a fixed version for your release line: 4.5.11 or 4.6.4.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-102831 being exploited?
There is no known exploitation of CVE-2026-102831 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-102831, GHSA-6966-vjj6-99xv, MINI-j59r-mhxf-xhgf, MINI-xc4q-827x-rjx8, PYSEC-2026-4057, PYSEC-2026-4058 and 3 more.