CVE-2026-35397

HIGH

jupyter-server path traversal allows access to sibling directories sharing root_dir name prefix

Title source: cna
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2026-35397. PoCs published by HiteshGorana.

AI-analyzed exploit summary This repository provides a detailed technical analysis and benchmark for CVE-2026-35397, a path traversal vulnerability in Jupyter Server. It includes functional and security tests, a masked vulnerable implementation, and a critique of the benchmark methodology.

Description

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.

Exploits (1)

nomisec WRITEUP
by HiteshGorana · poc
https://github.com/HiteshGorana/susvibes-jupyter-server-cve-2026-35397

This repository provides a detailed technical analysis and benchmark for CVE-2026-35397, a path traversal vulnerability in Jupyter Server. It includes functional and security tests, a masked vulnerable implementation, and a critique of the benchmark methodology.

Classification
Writeup 100%
Attack Type
Other
Complexity
Moderate
Reliability
Reliable
Target: Jupyter Server
No auth needed
Prerequisites: Jupyter Server installation · Python >=3.9 · uv for environment setup
mistral-large-3 · analyzed May 09, 2026 Full analysis →

Scores

CVSS v3 8.8
EPSS 0.0058
EPSS Percentile 43.6%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation poc
Automatable no
Technical Impact total

Details

CWE
CWE-22
Status published
Products (3)
jupyter/jupyter_server < 2.18.0
jupyter-server/jupyter_server < 2.18.0
pypi/jupyter-server 0 - 2.18.0PyPI
Published May 05, 2026
Tracked Since May 06, 2026