Auth bypass in Jupyter-Server Jupyter Server
CVE-2026-114135
Jupyter Server is the backend for Jupyter web applications. From 2.0.0 until 2.6.0, enabling GatewayClient.url replaced the normal KernelWebsocketHandler with WebSocketChannelsHandler, which authenticated the user but did not call authorizer.is_authorized(...) for the execute action on the kernels resource. A restricted authenticated user could therefore open an upstream kernel channel and obtain kernel execution despite the configured Authorizer denying that action, exposing data and credentials available to the kernel and permitting modification or disruption of the kernel environment. The default gateway configuration is fixed in version 2.6.0. In 2.6.0 and later, the same authorization bypass remains possible when a deployment manually registers the deprecated jupyter_server.gateway.handlers module, because its handler still omits the configured kernel-execute authorization decision.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Jupyter-Server Jupyter Server — versions >= 2.0.0, < 2.6.0
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-114135?
- CVE-2026-114135 is a high-severity vulnerability in Jupyter-Server Jupyter Server, classified under Missing Authorization. CVSS score: 8.8/10. Published 2026-10-21.
- How severe is CVE-2026-114135?
- High severity. CVSS v3 base score is 8.8 out of 10.