Medium 4.3Published May 22, 2026

CVE-2026-40864JupyterHub is software that allows users to create a multi-user server for Jupyter notebooks.

Updated under an hour ago (2026-10-19 07:30 UTC)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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: 4.3 MEDIUM (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
Weakness (CWE): CWE-352
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Not given
NVD analysis: Analyzed
Record last updated: Jul 23, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

jupyter jupyterhub jupyter:jupyterhub	from 4.1.0 before 5.4.5	NVD

References

https://github.com/jupyterhub/jupyterhub/commit/9c5ec277d3cda5a59de2d8c8117efa77bd941127patch
https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-m68r-v472-jgq9mitigation, vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.