{"cve":"CVE-2026-102830","nvd":{"published":"2026-09-29T19:17:25.527","modified":"2026-09-29T21:40:15.583","status":"Awaiting Analysis","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N","score":6.8},"cwes":["CWE-79","CWE-94"],"references":["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"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:56:48.555445741+00:00"},"epss":{"cve":"CVE-2026-102830","score":0.00261,"percentile":0.17623,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-3jqq-pw4j-pqcj","url":"https://osv.dev/vulnerability/GHSA-3jqq-pw4j-pqcj","summary":"JupyterLab: Cross-site scripting (XSS) in JupyterLab via crafted language package (jupyterlab.json)","modified":"2026-10-01T17:55:38.293412379Z","packages":[{"ecosystem":"PyPI","name":"jupyterlab","purl":"pkg:pypi/jupyterlab","ranges":[">=4.6.0 <4.6.4"],"fixed":["4.6.4"]},{"ecosystem":"PyPI","name":"jupyterlab","purl":"pkg:pypi/jupyterlab","ranges":[">=3.0.0 <4.5.11"],"fixed":["4.5.11"]},{"ecosystem":"PyPI","name":"jupyterlite-core","purl":"pkg:pypi/jupyterlite-core","ranges":["<0.8.4"],"fixed":["0.8.4"]}]},{"id":"PYSEC-2026-4056","url":"https://osv.dev/vulnerability/PYSEC-2026-4056","summary":"JupyterLab: Cross-site scripting (XSS) in JupyterLab via crafted language package (jupyterlab.json)","modified":"2026-10-01T17:55:38.293412379Z","packages":[{"ecosystem":"PyPI","name":"jupyterlab","purl":"pkg:pypi/jupyterlab","ranges":[">=3.0.0 <4.5.11",">=4.6.0 <4.6.4"],"fixed":["4.5.11","4.6.4"]}]},{"id":"PYSEC-2026-4059","url":"https://osv.dev/vulnerability/PYSEC-2026-4059","summary":"JupyterLab: Cross-site scripting (XSS) in JupyterLab via crafted language package (jupyterlab.json)","modified":"2026-10-01T17:55:38.293412379Z","packages":[{"ecosystem":"PyPI","name":"jupyterlite-core","purl":"pkg:pypi/jupyterlite-core","ranges":["<0.8.4"],"fixed":["0.8.4"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}