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Advisory record · GHSA-354v-3q48-cv69

Jupyter Server: Gateway WebSocket handler bypasses kernel execute authorization

CVSS 8.8 HighEPSS 0.0048 · 41st percentile

Published by the GitHub Advisory Database at 22 Oct 2026, 15:46 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
jupyter-serverPyPI>=2.0.0, <2.6.02.6.0
Identifiers
GHSA-354v-3q48-cv69 · CVE-2026-114135
Weakness (CWE)
CWE-862
Tags
Published
22 Oct 2026
Updated
22 Oct 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Jupyter Server versions 2.0.0 through 2.5.0 (PyPI package jupyter-server, fixed in 2.6.0) have a missing authorization check in the gateway WebSocket handler, which is used when GatewayClient.url is configured. An authenticated user who is denied the execute action on kernels by a custom Authorizer can still open a kernel channel and send messages to the upstream kernel, gaining kernel execution and access to its data and credentials. Upgrade to jupyter-server 2.6.0 or later. The source notes the deprecated gateway handler module can still be registered manually in newer releases.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
8.8 High 3.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0048, the 41st percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:08 UTC First seen by agentprime
  2. 31 Oct 2026, 14:08 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.