CVE-2026-114135

Name of the Vulnerable Software and Affected Versions Jupyter Server versions 2.0.0 through 2.6.0

Description An authorization bypass exists when GatewayClient.url is enabled, causing the KernelWebsocketHandler to be replaced by WebSocketChannelsHandler. While this handler authenticates the user, it fails to call the authorizer.is authorized() function for the execute action on the kernels resource. This allows a restricted authenticated user to open an upstream kernel channel and execute kernel commands even if the configured Authorizer denies the action, potentially exposing data and credentials or allowing modification of the kernel environment. This issue also persists in versions 2.6.0 and later if the deprecated jupyter server.gateway.handlers module is manually registered.

Recommendations Update to version 2.6.0. Avoid manually registering the deprecated jupyter server.gateway.handlers module in versions 2.6.0 and later.