CVE-2026-35397

What it is

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.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. High risk of data exposure, data tampering.

Exploit odds

0.6% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-05-05 20:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-08-28 16:17 UTC Last updatedMost recent change to the record

Details

Published

2026-05-05 20:16 UTC

Last modified

2026-08-28 16:17 UTC

Exploit probability

0.6% · EPSS, next 30 days

Weakness

CWE-22 · Path traversal

Record status

Modified

Affected

• Jupyter Server < 2.18.0

Attack profile CVSS 4.0 · 7.6

Attack vector

Network

Complexity

Low

Attack requirements

Present

Privileges needed

Low

User interaction

None

Confidentiality

High

Integrity

High

Availability

Low