CVE-2026-114135 with a CVSS score of 8.8 is a missing authorization vulnerability in Jupyter Server's gateway WebSocket handler, affecting Jupyter Server versions 2.0.0 through 2.5.0 when the default gateway configuration is used. The flaw occurs because the gateway-specific WebSocket handler verifies that a user is authenticated but does not consult the configured Authorizer to determine whether that user may execute kernels. In affected deployments, enabling GatewayClient.url automatically replaces the normal kernel channel handler with the gateway handler, so an authenticated user who is denied the execute action on the kernels resource can still open a kernel channel and send messages to the upstream kernel. The attack requires network access, low complexity, low privileges, and no user interaction, and it is not an authentication bypass but a failure to enforce intended authorization boundaries. Business impact includes allowing read-only or otherwise restricted users to obtain kernel execution, potentially exposing data, credentials, and other resources available to that kernel, which can undermine access controls and increase risk of data disclosure or malicious activity.
We recommend you to update Jupyter Server to version 2.6.0.[/subscribe_to_unlock_form]
CVE-2026-114135 with a CVSS score of 8.8 is a missing authorization vulnerability in Jupyter Server's gateway WebSocket handler, affecting Jupyter Server versions 2.0.0 through 2.5.0 when the default gateway configuration is used. The flaw occurs because the gateway-specific WebSocket handler verifies that a user is authenticated but does not consult the configured Authorizer to determine whether that user may execute kernels. In affected deployments, enabling GatewayClient.url automatically replaces the normal kernel channel handler with the gateway handler, so an authenticated user who is denied the execute action on the kernels resource can still open a kernel channel and send messages to the upstream kernel. The attack requires network access, low complexity, low privileges, and no user interaction, and it is not an authentication bypass but a failure to enforce intended authorization boundaries. Business impact includes allowing read-only or otherwise restricted users to obtain kernel execution, potentially exposing data, credentials, and other resources available to that kernel, which can undermine access controls and increase risk of data disclosure or malicious activity.
We recommend you to update Jupyter Server to version 2.6.0.[emaillocker id="1283"]
The following reports contain further technical details:
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