Jupyter Server Path Traversal Vulnerability in REST API Allowing Unauthorized Directory Access

A path traversal vulnerability has been identified in Jupyter Server versions through 2.17.0. This vulnerability allows an authenticated user to escape the designated root directory and access sibling directories that share a prefix with the root directory name. For instance, if the root directory is named 'test', an attacker could access a sibling directory called 'testtest' by sending a crafted request to the /api/contents endpoint with encoded path components. This vulnerability enables the reading, writing, and deletion of files in the affected sibling directories. It poses a significant risk in multi-tenant deployments with predictable naming conventions, as users could potentially access each other's directories.

Impact

Exploitation of this vulnerability allows authenticated users to access, modify, and delete files in sibling directories outside their designated root directory, with particularly severe implications in multi-tenant environments.

Reproduction

To reproduce this vulnerability, an authenticated user can send a POST request to the /api/contents endpoint, using encoded path components to traverse out of the root directory and into a sibling directory that shares a prefix with the root directory name. This can be done using tools like curl, by specifying the target sibling directory and the file to be accessed or manipulated.

Remediation

Users are advised to update to Jupyter Server version 2.18.0 or later. As an additional precaution, ensure that folder names do not overlap with sibling directories.