CVE-2026-35397Public exploitNetwork attack vectorHinoki check available

Sibling file access via string-prefix containment check

Published May 5, 2026 · Updated May 5, 2026

Path traversal in Jupyter Server 2.17.0 and earlier allows remote authenticated users to read, write, or delete sibling-directory files. FileManagerMixin._get_os_path normalizes an API path but tests containment with a plain string-prefix comparison, so ../ paths into a sibling such as testtest pass when root_dir is test. Exploitation requires an authenticated /api/contents request and a sibling name sharing the configured root prefix, a pattern common in predictable multi-tenant directory schemes.

CVSS severity7.6
High
EPSS probability0.62%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Path traversal in Jupyter Server 2.17.0 and earlier allows remote authenticated users to read, write, or delete sibling-directory files. FileManagerMixin._get_os_path normalizes an API path but tests containment with a plain string-prefix comparison, so ../ paths into a sibling such as testtest pass when root_dir is test. Exploitation requires an authenticated /api/contents request and a sibling name sharing the configured root prefix, a pattern common in predictable multi-tenant directory schemes.

The record

CVE
CVE-2026-35397
Published
May 5, 2026
Updated
May 5, 2026
Vendor
Project Jupyter
Product
Jupyter Server
Classifications
CWE-22, T1005
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 5, 2026CVE publishedPublication date reported by the CVE source.
  2. May 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.18.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Project Jupyter · Jupyter Serverversion=< 2.18.0

Published CVSS scores

7.1Red HatCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.1GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L
7.6GitHub, Inc.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

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1005Data from Local System

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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