{"cve":"CVE-2026-35397","nvd":{"published":"2026-05-05T20:16:38.223","modified":"2026-08-28T16:17:45.870","status":"Modified","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. \n\nVersion 2.18.0 contains a fix. As a workaround, ensure folder names do not share a common prefix with any sibling directory.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N","score":7.6},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":8.8},"cwes":["CWE-22"],"references":["https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-5789-5fc7-67v3","https://access.redhat.com/errata/RHSA-2026:43038","https://access.redhat.com/errata/RHSA-2026:60520","https://access.redhat.com/security/cve/CVE-2026-35397","https://bugzilla.redhat.com/show_bug.cgi?id=2466858"],"products":["jupyter:jupyter_server"],"source":"nvd","synced_at":"2026-10-19T22:33:55.586217763+00:00"},"epss":{"cve":"CVE-2026-35397","score":0.00622,"percentile":0.49814,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-5789-5fc7-67v3","url":"https://osv.dev/vulnerability/GHSA-5789-5fc7-67v3","summary":"Jupyter Server: Path Traversal via incorrect startswith() root directory check allows access to sibling directories","modified":"2026-09-10T03:51:04.602794828Z","packages":[{"ecosystem":"PyPI","name":"jupyter-server","purl":"pkg:pypi/jupyter-server","ranges":["<2.18.0"],"fixed":["2.18.0"]}]},{"id":"PYSEC-2026-68","url":"https://osv.dev/vulnerability/PYSEC-2026-68","summary":"","modified":"2026-05-20T09:19:02.924837Z","packages":[{"ecosystem":"PyPI","name":"jupyter-server","purl":"pkg:pypi/jupyter-server","ranges":["<2.18.0"],"fixed":["2.18.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}