CVE-2026-35397
8.8 · HIGHOverview
CVE-2026-35397 is a high-severity vulnerability affecting jupyter jupyter_server. It was published on May 5, 2026 and has a CVSS 3.1 base score of 8.8 (HIGH).
This vulnerability has a CVSS 3.1 base score of 8.8, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.
Technical 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.
Remediation
Check the references section for vendor advisories and patches from jupyter. Update jupyter_server to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| jupyter | jupyter_server | >= 0, < 2.18.0 | Affected |
References
Frequently Asked Questions
What is CVE-2026-35397?
CVE-2026-35397 is a high-severity vulnerability affecting jupyter jupyter_server. It was published on May 5, 2026 and has a CVSS 3.1 base score of 8.8 (HIGH).
How severe is CVE-2026-35397?
This vulnerability has a CVSS 3.1 base score of 8.8, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.
How do I fix or remediate CVE-2026-35397?
Check the references section for vendor advisories and patches from jupyter. Update jupyter_server to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-35397?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-35397 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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