{"cve":"CVE-2026-40864","nvd":{"published":"2026-05-22T21:16:43.177","modified":"2026-07-23T11:10:00.120","status":"Analyzed","description":"JupyterHub is software that allows users to create a multi-user server for Jupyter notebooks. In versions 4.1.0 through 5.4.4, XSRF protection (updated in 4.1.0) inappropriately treated requests with Sec-Fetch-Mode: no-cors as same-origin requests, bypassing XSRF checks. The JSON API is not affected, only HTTP form endpoints, such as /hub/spawn and /hub/accept-share, meaning attackers could trigger server spawn (but not access the server) and if the attacker is a JupyterHub user permitted to share access to their server, cause a user to accept a share and have access to the attacker's server. This issue has been fixed in version 5.4.5. If developers are unable to immediately upgrade, they can temporarily mitigate this issue by dropping requests to JupyterHub with Sec-Fetch-Mode: no-cors if they are using a reverse proxy.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N","score":4.3},"cwes":["CWE-352"],"references":["https://github.com/jupyterhub/jupyterhub/commit/9c5ec277d3cda5a59de2d8c8117efa77bd941127","https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-m68r-v472-jgq9"],"products":["jupyter:jupyterhub"],"source":"nvd","synced_at":"2026-10-19T22:36:28.938604137+00:00"},"epss":{"cve":"CVE-2026-40864","score":0.00146,"percentile":0.03815,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-m68r-v472-jgq9","url":"https://osv.dev/vulnerability/GHSA-m68r-v472-jgq9","summary":"JupyterHub has cross-origin form POSTs bypass XSRF (CWE-352)","modified":"2026-09-10T03:51:06.307577438Z","packages":[{"ecosystem":"PyPI","name":"jupyterhub","purl":"pkg:pypi/jupyterhub","ranges":[">=4.1.0 <5.4.5"],"fixed":["5.4.5"]}]},{"id":"PYSEC-2026-2189","url":"https://osv.dev/vulnerability/PYSEC-2026-2189","summary":"","modified":"2026-07-13T07:26:16.328743594Z","packages":[{"ecosystem":"PyPI","name":"jupyterhub","purl":"pkg:pypi/jupyterhub","ranges":[">=4.1.0 <5.4.5"],"fixed":["5.4.5"]}]}],"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."]}