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Fencer Vulns
high 7.1

CVE-2026-35397 json

jupyter-server path traversal allows access to sibling directories sharing root_dir name prefix

published 2026-05-05 6 mo ago modified 2026-09-10 1 mo ago also GHSA-5789-5fc7-67v3 , PYSEC-2026-68 , EUVD-2026-27470

cvss
7.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits
0
none known

Summary

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.

Patch / fix

  • pypi jupyter-server 2.18.0
  • Red Hat Red Hat Migration Toolkit for Applications 8.2 1784109883
  • Red Hat Red Hat OpenShift AI 3.4 1787073546, 1787073593, 1787073605, 1787073713, 1787073717, 1787073913, 1787073929, 1787074078, 1787074331, 1787076481, 1787076778, 1787077779
  • jupyter-server Debian 14 2.20.0-1

debian advisories DEBIAN-CVE-2026-35397

  • python-jupyter-server openSUSE Tumbleweed 2.18.1-1.1

opensuse advisories openSUSE-SU-2026:10710-1

  • jupyter-server Alpine 3.24 2.18.2-r0

alpine advisories ALPINE-CVE-2026-35397

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-35397 updated cvss 7.1

jupyter-server: Jupyter Server: Unauthorized File Access via Path Traversal Vulnerability

  • Red Hat Migration Toolkit for Applications 8.2 mta/mta-solution-server-rhel9 1784109883
    fixed: vendor fix RHSA-2026:43038
  • Red Hat OpenShift AI 3.3 rhoai/odh-workbench-jupyter-minimal-cpu-py312-rhel9 1790260954, rhoai/odh-workbench-jupyter-minimal-cuda-py312-rhel9 1790072130, rhoai/odh-workbench-jupyter-minimal-rocm-py312-rhel9 1790072109, rhoai/odh-workbench-jupyter-pytorch-cuda-py312-rhel9 1789651387, rhoai/odh-workbench-jupyter-pytorch-rocm-py312-rhel9 1789651385, rhoai/odh-workbench-jupyter-trustyai-cpu-py312-rhel9 1790260954, +4 more
    fixed: vendor fix RHSA-2026:73987
  • Red Hat OpenShift AI 3.4 rhoai/odh-th06-cpu-torch210-py312-rhel9 1787076778, rhoai/odh-th06-rocm64-torch291-py312-rhel9 1787076481, rhoai/odh-th06-cuda130-torch210-py312-rhel9 1787077779, rhoai/odh-workbench-jupyter-minimal-cpu-py312-rhel9 1787073913, rhoai/odh-workbench-jupyter-minimal-cuda-py312-rhel9 1787074078, rhoai/odh-workbench-jupyter-minimal-rocm-py312-rhel9 1787073929, +6 more
    fixed: vendor fix RHSA-2026:60520
  • Red Hat Migration Toolkit for Applications 8.2 mta/mta-ui-rhel9 1783962515, mta/mta-cli-rhel9 1784211378, mta/mta-hub-rhel9 1784059743, mta/mta-rhel9-operator 1784219586, mta/mta-operator-bundle 1784220119, mta/mta-analyzer-addon-rhel9 1784163267, +7 more
    not affected: vulnerable code not present
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-th06-cpu-torch291-py312-rhel9, rhoai/odh-th06-cuda130-torch291-py312-rhel9
    not affected: component not present
  • Red Hat OpenShift AI 3.3 rhoai/odh-cli-rhel9 1790070206, rhoai/rhai-cli-rhel9 1790070206, rhoai/odh-mlflow-rhel9 1789653606, rhoai/odh-trainer-rhel9 1790136369, rhoai/odh-maas-api-rhel9 1790131842, rhoai/odh-mlserver-rhel9 1789121365, +67 more Red Hat OpenShift AI 3.4 rhoai/odh-cli-rhel9 1787330837, rhoai/rhai-cli-rhel9 1787330837, rhoai/odh-automl-rhel9 1786612415, rhoai/odh-mlflow-rhel9 1787226790, rhoai/odh-autorag-rhel9 1786612637, rhoai/odh-trainer-rhel9 1787089049, +88 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
6 mo ago

Exploit prediction

0.62% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-5789-5fc7-67v3 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 7.6 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
CISA ADP 3.1 7.1 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L
CNA 4.0 7.6 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 7.1 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L
OSV 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
GitHub 3.1 7.1 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L

Affected packages

ecosystem package affected fixed in
pypi jupyter-server
<2.18.0
2.18.0

Affected products

  • jupyter-server jupyter_server
  • Red Hat Red Hat Migration Toolkit for Applications 8.2
  • Red Hat Red Hat OpenShift AI 3.4
  • Red Hat Red Hat OpenShift AI (RHOAI)

Classification

Weakness
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.