Medium 5.4Published May 22, 2026

CVE-2026-40864JupyterHub: Cross-origin form POSTs bypass XSRF

Updated under an hour ago (Oct 28, 2026, 7:30 AM ET)

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It affects jupyterhub and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for jupyterhub

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: 5.4 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L
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: GitHub_M
NVD analysis: Analyzed
Record last updated: May 26, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

jupyterhub jupyterhub jupyterhub:jupyterhub (from the name)	from 4.1.0, < 5.4.5	CNA record
jupyter jupyterhub jupyter:jupyterhub	from 4.1.0 before 5.4.5	NVD

References

References

https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-m68r-v472-jgq9	x-refsource-confirm, mitigation, vendor-advisory
https://github.com/jupyterhub/jupyterhub/commit/9c5ec277d3cda5a59de2d8c8117efa77bd941127	x-refsource-misc, patch

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.