CVE-2026-102830 · GHSA-3jqq-pw4j-pqcj
JupyterLab: Cross-site scripting (XSS) in JupyterLab via crafted language package (jupyterlab.json)
- Risk score
- 49/100
- CVSS
- 6.8 v3.1
- Exploit chance (30 days)
- 0.3%
- Published
- 29 Sep 2026
Open in the live forecast Today's forecast
What to know
- What it is
- JupyterLab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture. From JupyterLab 3.0.0 until 4.5.11 and 4.6.4, and in JupyterLite Core 0.8.3 and earlier, the Plural-Forms header in a selected third-party language pack can append JavaScript after a valid pl…
- Affected
- jupyterlab (pip) >= 4.6.0, <= 4.6.3; jupyterlab (pip) >= 3.0.0, <= 4.5.10; jupyterlite-core (pip) <= 0.8.3
- Fix
- Upgrade jupyterlab to 4.6.4 or 4.5.11; jupyterlite-core to 0.8.4 (whichever matches your release line) or later.
- Exploitation
- No known exploitation
Why it is Yellow
- CVSS 6.8 medium
- On your watchlist: PyPI
Affected packages
| Package | Ecosystem | Vulnerable | Fixed in |
|---|---|---|---|
| jupyterlab | pip | >= 4.6.0, <= 4.6.3 | 4.6.4 |
| jupyterlab | pip | >= 3.0.0, <= 4.5.10 | 4.5.11 |
| jupyterlite-core | pip | <= 0.8.3 | 0.8.4 |
References
- https://github.com/advisories/GHSA-3jqq-pw4j-pqcj
- https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-3jqq-pw4j-pqcj
- https://nvd.nist.gov/vuln/detail/CVE-2026-102830
- https://github.com/jupyterlab/jupyterlab/commit/985a3223cd77fd4f991cd90066342a90711d70f6
- https://github.com/jupyterlab/jupyterlab/commit/de324ae91346c713c4f5e5485f97b6e914e0f774
- https://github.com/jupyterlab/jupyterlab/commit/f9de43dc565a1118120d466117f877a189a4ce90
- https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.11
- https://github.com/jupyterlab/jupyterlab/releases/tag/v4.6.4
- https://github.com/advisories/GHSA-3jqq-pw4j-pqcj
Original description
JupyterLab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture. From JupyterLab 3.0.0 until 4.5.11 and 4.6.4, and in JupyterLite Core 0.8.3 and earlier, the Plural-Forms header in a selected third-party language pack can append JavaScript after a valid plural rule because prefix-only regular-expression validation accepts a matching prefix without requiring the entire header to match. JupyterLab passes the accepted expression to new Function, so loading the catalogue and translating a plural string executes the appended code in the authenticated JupyterLab origin. Where Jupyter Server kernels, terminals, and APIs are exposed, the code can use authenticated server APIs to read or modify files and run code. Impact is much more limited in JupyterLite because it typically lacks most exposed Jupyter Server surfaces. The default English locale is unaffected because it does not load a translation catalogue. This issue is fixed in JupyterLab 4.5.11 and 4.6.4 and JupyterLite Core 0.8.4.
Last activity 29 Sep 2026. Patch Forecast updates every hour.