CVE-2026-114135 Jupyter Server: Gateway WebSocket handler bypasses kernel execute authorization

What is CVE-2026-114135?

CVE-2026-114135 is a high-severity vulnerability in jupyter-server jupyter_server, published on 21 Oct 2026.

Official description

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.

Weakness: CWE-862

Which versions are affected by CVE-2026-114135?

2 open source packages ship an affected version, including jupyter-server.

How do I fix CVE-2026-114135?

Upgrade jupyter-server to 2.6.0 or later.

Is CVE-2026-114135 being exploited?

There is no known exploitation of CVE-2026-114135 in the wild and no public exploit code.

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2026-114135, GHSA-354v-3q48-cv69, UBUNTU-CVE-2026-114135.