Bug 2466858 (CVE-2026-35397)

Summary: CVE-2026-35397 jupyter-server: Jupyter Server: Unauthorized File Access via Path Traversal Vulnerability
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: jkoehler, lphiri, rjohnson
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Jupyter Server. An authenticated user can exploit a path traversal vulnerability in the REST API to escape the configured root directory (`root_dir`). By crafting a request to the `/api/contents` endpoint with encoded path components, an attacker can gain access to sibling directories whose names begin with the same prefix as the `root_dir`. This allows the attacker to read, write, and delete files in these accessible sibling directories, potentially leading to unauthorized data access and modification, especially in multi-tenant environments.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2484706, 2484708    
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Description OSIDB Bzimport 2026-05-05 20:01:42 UTC 
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.