---
id: CVE-2026-35397
title: Jupyter Server is the backend for Jupyter web applications
summary: >-
  Jupyter Server is the backend for Jupyter web applications. In versions 2.17.0
  and earlier, a path traversal vulnerability in the REST API allows an
  authenticated user to escape the configured root_dir and access sibling
  directories whos…
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'
cwe:
  - CWE-22
vendor: jupyter
product: jupyter_server
affected:
  - jupyter_server < 2.18.0
patched:
  - jupyter_server 2.18.0
published: '2026-05-05'
updated: '2026-07-22'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-35397'
references:
  - url: >-
      https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-5789-5fc7-67v3
    label: security-advisories@github.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:43038'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/security/cve/CVE-2026-35397'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2466858'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: >-
      https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-5789-5fc7-67v3
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-35397.json
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-35397'
  - url: 'https://access.redhat.com/errata/RHSA-2026:60520'
  - url: 'https://github.com/jupyter-server/jupyter_server'
  - url: >-
      https://github.com/pypa/advisory-database/tree/main/vulns/jupyter-server/PYSEC-2026-68.yaml
tags:
  - nvd
  - exploit-available
  - osv
  - pip
epss: 0.00622
epssPercentile: 0.48436
ingestedAt: '2026-07-22T13:03:40.771Z'
exploits:
  github: 1
  githubRepos:
    - 'https://github.com/HiteshGorana/susvibes-jupyter-server-cve-2026-35397'
  checkedAt: '2026-09-23T07:14:02.167Z'
exploitAvailable: true
aliases:
  - GHSA-5789-5fc7-67v3
  - PYSEC-2026-68
ecosystem: pip
scores:
  nvd: 8.8
  osv: 7.1
---

## Overview

Jupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, a path traversal vulnerability in the REST API allows an authenticated user to escape the configured root_dir and access sibling directories whose names begin with the same prefix as the root_dir. For example, with a root_dir named "test", the API permits access to a sibling directory named "testtest" through a crafted request to the /api/contents endpoint using encoded path components. An attacker can read, write, and delete files in affected sibling directories. Multi-tenant deployments using predictable naming schemes are particularly at risk, as a user with a directory named "user1" could access directories for user10 through user19 and beyond. A user who can choose a single-character folder name could gain access to a significant number of sibling directories. 

Version 2.18.0 contains a fix. As a workaround, ensure folder names do not share a common prefix with any sibling directory.

## Affected

- `jupyter_server < 2.18.0`

## Remediation

Upgrade past the affected range:

- `jupyter_server 2.18.0`

## Package advisory (CVE-2026-35397)

Affected packages:

- `jupyter-server < 2.18.0`

Patched in:

- `jupyter-server 2.18.0`

Source: https://osv.dev/vulnerability/GHSA-5789-5fc7-67v3