Jupyter jupyter_server up to 2.17.0 fileio.py _get_os_path path traversal

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Jupyter jupyter_server up to 2.17.0. Affected by this issue is the function _get_os_path of the file jupyter_server/services/contents/fileio.py. The manipulation leads to path traversal. This vulnerability is uniquely identified as CVE-2026-5422. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability was found in Jupyter jupyter_server up to 2.17.0 and classified as problematic. This issue affects the function _get_os_path of the file jupyter_server/services/contents/fileio.py. The manipulation with an unknown input leads to a path traversal vulnerability. Using CWE to declare the problem leads to CWE-23. The product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize sequences such as ".." that can resolve to a location that is outside of that directory. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at huntr.com. The identification of this vulnerability is CVE-2026-5422 since 04/02/2026. The exploitation is known to be difficult. The attack may be initiated remotely. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 06/02/2026). The attack technique deployed by this issue is T1006 according to MITRE ATT&CK.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-33905). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

• Jupyter

Name

• jupyter_server

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6
• 2.7
• 2.8
• 2.9
• 2.10
• 2.11
• 2.12
• 2.13
• 2.14
• 2.15
• 2.16
• 2.17.0

CPE 2.3info

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• 🔒
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CPE 2.2info

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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