Cross-site Request Forgery (CSRF) Affecting jupyterhub package, versions [4.1.0,5.4.5)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-JUPYTERHUB-16425791
- published6 May 2026
- disclosed5 May 2026
- creditRomain Deperne
Introduced: 5 May 2026
CVE-2026-40864 (opens in a new tab)How to fix?
Upgrade jupyterhub to version 5.4.5 or higher.
Overview
jupyterhub is a JupyterHub: A multi-user server for Jupyter notebooks
Affected versions of this package are vulnerable to Cross-site Request Forgery (CSRF) in the handling of HTTP form endpoints when requests with the Sec-Fetch-Mode: no-cors header are incorrectly treated as same-origin, bypassing intended security checks. An attacker can trigger server spawn actions or cause a user to accept a server share by enticing them to visit a malicious site and submit a crafted form.
Note: This is only exploitable if the attacker is a permitted user and the victim is authenticated in the application.
Workaround
This vulnerability can be mitigated by configuring a reverse proxy to drop requests with the Sec-Fetch-Mode: no-cors header.