CVE-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 API is not affecte...

CVE-2026-40864

Affected software: JupyterHub (versions 4.1.0–5.4.4). Vulnerability: Cross-origin form POSTs bypass XSRF because XSRF protection treated requests with Sec-Fetch-Mode: no-cors as same-origin, affecting HTTP form endpoints (e.g., /hub/spawn, /hub/accept-share). The JSON API is not affected. Impact ...