Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Jupyter | Jupyter Server | < 2.18.0 |
Related Weaknesses (CWE)
References
- https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-5789-5ExploitVendor Advisory
- https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-5789-5ExploitVendor Advisory
FAQ
What is CVE-2026-35397?
CVE-2026-35397 is a vulnerability with a CVSS score of 8.8 (HIGH). 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_di...
How severe is CVE-2026-35397?
CVE-2026-35397 has been rated HIGH with a CVSS base score of 8.8/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-35397?
Check the references section above for vendor advisories and patch information. Affected products include: Jupyter Jupyter Server.