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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.

PUBLISHED Reserved 2026-04-02 | Published 2026-05-05 | Updated 2026-05-06 | Assigner GitHub_M




HIGH: 7.6CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N

Problem types

CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Product status

< 2.18.0
affected

References

github.com/...server/security/advisories/GHSA-5789-5fc7-67v3 exploit

github.com/...server/security/advisories/GHSA-5789-5fc7-67v3

cve.org (CVE-2026-35397)

nvd.nist.gov (CVE-2026-35397)

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