CVE-2026-35397High· 8.8▾ MidnightPoC availableJupyter 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 whos…
▾ Midnight zone — Critical, or high with PoC / in-the-wild
impact 48.4 · likelihood 0.1 · exploitation 12
A public proof-of-concept already exists for this vulnerability — see Exploit availability below.
Public exploit / PoC code seen in 1 source. Availability, not in-the-wild use.
Exploit-prediction probability, daily snapshots since Jul 30.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
Last analysed / modified upstream
0.6%
1 GitHub repo
0.6% → 0.7%
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.
jupyter_server < 2.18.0Upgrade past the affected range:
jupyter_server 2.18.0Affected packages:
jupyter-server < 2.18.0Patched in:
jupyter-server 2.18.0Field changes observed since this record was first indexed.
Connected by shared product, vendor, weakness, or advisory.
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