https://cve.radiocsirt.org/rss/recent/all/10 Most recent entries from all 2026-10-04T02:20:54.824765+00:00 Vulnerability-Lookup csirt@opendfir.org python-feedgen Contains only the most 10 recent entries. https://cve.radiocsirt.org/vuln/cve-2026-40864 CVE-2026-40864 — JupyterHub: Cross-origin form POSTs bypass XSRF 2026-10-04T02:20:54.826513+00:00

Affected: 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.

 https://cve.radiocsirt.org/vuln/ghsa-m68r-v472-jgq9 GHSA-m68r-v472-jgq9 — JupyterHub has cross-origin form POSTs bypass XSRF (CWE-352) 2026-10-04T02:20:54.826596+00:00

Affected: PyPI: jupyterhub

## Summary

JupyterHub's XSRF protection (updated in 4.1.0) inappropriately treated requests with `Sec-Fetch-Mode: no-cors` as same-origin requests, which they are not, 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.

## Patches

Upgrade to JupyterHub 5.4.5.

## Mitigations

If a reverse proxy is in use, drop requests to JupyterHub with `Sec-Fetch-Mode: no-cors`.