CVE-2026-40864Medium· 5.4▾ TwilightPoC availableJupyterHub has cross-origin form POSTs bypass XSRF (CWE-352)
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 29.7 · likelihood 0 · exploitation 12
A public proof-of-concept already exists for this vulnerability — see Exploit availability below.
Public exploit / PoC code seen in 1 source. Availability, not in-the-wild use.
Exploit-prediction probability, daily snapshots since Jul 13.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via OSV
0.2%
1 GitHub repo
Last analysed / modified upstream
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.
Upgrade to JupyterHub 5.4.5.
If a reverse proxy is in use, drop requests to JupyterHub with Sec-Fetch-Mode: no-cors.
jupyterhub >= 4.1.0, < 5.4.5Upgrade to a patched release:
jupyterhub 5.4.5Field changes observed since this record was first indexed.
Connected by shared product, vendor, weakness, or advisory.
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CVE-2026-54338Medium· 5.3JupyterHub has Unauthenticated Denial of Service via Unbounded Username Logging on Failed Login
CVE-2026-33709Medium· 6.1JupyterHub has an Open Redirect Vulnerability
CVE-2021-41247Low· 3.5incomplete JupyterHub logout with simultaneous JupyterLab sessions
CVE-2024-28233High· 8.1Cross site scripting (XSS) in JupyterHub via Self-XSS leveraged by Cookie Tossing