---
id: CVE-2026-114135
title: >-
  Jupyter Server: Gateway WebSocket handler bypasses kernel execute
  authorization
summary: >-
  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
  author…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
cwe:
  - CWE-862
vendor: jupyter-server
product: jupyter_server
affected:
  - 'jupyter_server >= 2.0.0, < 2.6.0'
published: '2026-10-21'
updated: '2026-10-21'
sourceUpdated: '2026-10-21T19:58:51.544Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-114135'
references:
  - url: >-
      https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-354v-3q48-cv69
    label: >-
      https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-354v-3q48-cv69
  - url: 'https://github.com/jupyter-server/jupyter_server/pull/1261'
    label: 'https://github.com/jupyter-server/jupyter_server/pull/1261'
  - url: >-
      https://github.com/jupyter-server/jupyter_server/commit/35ffe5d435682128da16dc144a8e9e9f8fa85dd8
    label: >-
      https://github.com/jupyter-server/jupyter_server/commit/35ffe5d435682128da16dc144a8e9e9f8fa85dd8
  - url: 'https://github.com/jupyter-server/jupyter_server/releases/tag/v2.6.0'
    label: 'https://github.com/jupyter-server/jupyter_server/releases/tag/v2.6.0'
tags:
  - cve.org
ingestedAt: '2026-10-21T20:11:44.902Z'
---

## Overview

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.

## Affected

- `jupyter_server >= 2.0.0, < 2.6.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.