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Vulnerabilities

Vulnerability · CVE-2026-40864

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

Published May 22, 2026 · catalog updated Jul 23, 2026 · JupyterHub is software that

Check if you run it

No confirmed exploitation is on record for CVE-2026-40864. EPSS is 0.18%. Act only if a listed version of JupyterHub is software that is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (JupyterHub is software that).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium4.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.18%
Remediation
Advisory link
Affected products
cpe jupyter/jupyterhub

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe jupyter/jupyterhubversion unspecified

How to fix CVE-2026-40864

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-40864. EPSS is 0.18%. Act only if a listed version of JupyterHub is software that is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-352: Cross-Site Request Forgery (CSRF). EPSS 0.18%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. May 22, 2026 · NIST NVD

    Detected

    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 trigge

  2. Jul 23, 2026 · NIST NVD

    Updated

    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 trigge

Sources

  • CVE.orgVulnerability recordCVE-2026-40864

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-40864

    30-day exploitation probability 0.2%

    first.org
  • NIST NVDVulnerability recordCVE-2026-40864

    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

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.