{"cve":"CVE-2026-40171","nvd":{"published":"2026-05-06T20:16:31.857","modified":"2026-10-26T19:10:00.163","status":"Awaiting Analysis","description":"In Jupyter Notebook versions 7.0.0 through 7.5.5, JupyterLab versions 4.5.6 and earlier, and the corresponding @jupyter-notebook/help-extension and @jupyterlab/help-extension packages before 7.5.6 and 4.5.7, a stored cross-site scripting issue in the help command linker can be chained with attacker-controlled notebook content to steal authentication tokens with a single click.\n\nAn attacker can craft a malicious notebook file containing elements that appear indistinguishable from legitimate controls and trigger execution when a user interacts with them. Successful exploitation allows theft of the user's authentication token and complete takeover of the Jupyter session through the REST API, including reading files, creating or modifying files, accessing kernels to execute arbitrary code, and creating terminals for shell access. This issue has been fixed in Notebook 7.5.6, JupyterLab 4.5.7, @jupyter-notebook/help-extension 7.5.6, and @jupyterlab/help-extension 4.5.7. As a workaround, disable the affected help extensions or set allowCommandLinker to false in the sanitizer configuration.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","score":8.4},"cvss_v3":null,"cwes":["CWE-79"],"references":["https://github.com/jupyter/notebook/security/advisories/GHSA-rch3-82jr-f9w9"],"products":[],"source":"nvd","synced_at":"2026-10-26T19:31:02.781428341+00:00"},"epss":{"cve":"CVE-2026-40171","score":0.00476,"percentile":0.40884,"date":"2026-10-26"},"kev":null,"osv":[{"id":"GHSA-rch3-82jr-f9w9","url":"https://osv.dev/vulnerability/GHSA-rch3-82jr-f9w9","summary":"Jupyter Notebook Vulnerable to Authentication Token Theft via CommandLinker XSS","modified":"2026-09-10T03:51:03.066267538Z","packages":[{"ecosystem":"npm","name":"@jupyter-notebook/help-extension","purl":"pkg:npm/%40jupyter-notebook/help-extension","ranges":[">=7.0.0 <7.5.6"],"fixed":["7.5.6"]},{"ecosystem":"PyPI","name":"notebook","purl":"pkg:pypi/notebook","ranges":[">=7.0.0 <7.5.6"],"fixed":["7.5.6"]},{"ecosystem":"PyPI","name":"jupyterlab","purl":"pkg:pypi/jupyterlab","ranges":["<4.5.7"],"fixed":["4.5.7"]},{"ecosystem":"npm","name":"@jupyterlab/help-extension","purl":"pkg:npm/%40jupyterlab/help-extension","ranges":["<4.5.7"],"fixed":["4.5.7"]}]},{"id":"PYSEC-2026-2538","url":"https://osv.dev/vulnerability/PYSEC-2026-2538","summary":"Jupyter Notebook Vulnerable to Authentication Token Theft via CommandLinker XSS","modified":"2026-07-13T16:42:47.886298772Z","packages":[{"ecosystem":"PyPI","name":"jupyterlab","purl":"pkg:pypi/jupyterlab","ranges":["<4.5.7"],"fixed":["4.5.7"]}]},{"id":"PYSEC-2026-2682","url":"https://osv.dev/vulnerability/PYSEC-2026-2682","summary":"Jupyter Notebook Vulnerable to Authentication Token Theft via CommandLinker XSS","modified":"2026-07-13T16:42:47.886298772Z","packages":[{"ecosystem":"PyPI","name":"notebook","purl":"pkg:pypi/notebook","ranges":[">=7.0.0 <7.5.6"],"fixed":["7.5.6"]}]}],"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."]}