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Vulnerability record · CVE-2026-5422 · published 2 June 2026

CVE-2026-5422: Jupyter server relative path traversal vulnerability

Jupyter · Jupyter Server

A path traversal vulnerability exists in jupyter-server version 2.17.0 due to an incorrect root directory boundary check in the _get_os_path() function within jupyter_server/services/contents/fileio.py. The check uses startswith(root) without appending a trailing path separator, allowing sibling directories with names starting with the same prefix as root_dir to bypass the check. Additionally, the to_os_path() function in utils.py does not strip ".." from path parts, enabling traversal sequences to bypass the vulnerable check. This vulnerability can lead to unauthorized read/write access to files in sibling directories, potentially exposing sensitive data in shared hosting environments.

8.1 CVSS 3.1 High EPSS 0.55% · top 56.3% CWE-23 · Relative path traversal
8.1CVSS 3.1 base score
0.55%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References, 2 tagged exploit
22 Jul 2026Last modified by NVD

Description

A path traversal vulnerability exists in jupyter-server version 2.17.0 due to an incorrect root directory boundary check in the _get_os_path() function within jupyter_server/services/contents/fileio.py. The check uses startswith(root) without appending a trailing path separator, allowing sibling directories with names starting with the same prefix as root_dir to bypass the check. Additionally, the to_os_path() function in utils.py does not strip ".." from path parts, enabling traversal sequences to bypass the vulnerable check. This vulnerability can lead to unauthorized read/write access to files in sibling directories, potentially exposing sensitive data in shared hosting environments.

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://huntr.com/bounties/24a36953-6490-466f-8cb2-a90d1ca56e0f ExploitThird Party Advisory
https://huntr.com/bounties/24a36953-6490-466f-8cb2-a90d1ca56e0f ExploitThird Party Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-5422), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.