CVE-2026-35397

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.

Weakness classification

• security-advisories@github.com: CWE-22
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c: CWE-22

Primary references

• security-advisories@github.com — Exploit, Vendor Advisory
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
• 134c704f-9b21-4f2e-91b3-4a467353bcc0 — Exploit, Vendor Advisory
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c