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Public proof of conceptFix available

CVE-2026-5422

A public proof of concept exists; no exploitation attested.

  • Published2026-06-02
  • Fixed in2.18.2
  • WeaknessCWE-23

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2026-06-0210:16CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-25 15:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-5422?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-5422?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

OSV · NVD
jupyter-server
BranchAffectedFixed in
2.18< 2.18.22.18.2
Jupyter jupyter server
BranchAffectedFixed in
2.17= 2.17.0no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

  • RHSA-2026:73987 Red Hat Product Security21 products fixed

    Red Hat Security Advisory: RHOAI 3.3.7 - Red Hat OpenShift AI

  • RHSA-2026:60520 Red Hat Product Security25 products fixed

    Red Hat Security Advisory: RHOAI 3.4.4 - Red Hat OpenShift AI

  • RHSA-2026:43038 Red Hat Product Security2 products fixed

    Red Hat Security Advisory: Migration Toolkit for Applications

Full record on NVD

Fix

  1. Update jupyter-server to 2.18.2
  2. Vendor fix Red Hat Product Security RHSA-2026:73987 · 21 productsFor Red Hat OpenShift AI 3.3.7 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this errata update: https://docs.redhat.com/en/documentation/red_hat_openshift_ai/
  3. Vendor fix Red Hat Product Security RHSA-2026:60520 · 25 productsFor Red Hat OpenShift AI 3.4.4 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this errata update: https://docs.redhat.com/en/documentation/red_hat_openshift_ai/
  4. Vendor fix Red Hat Product Security RHSA-2026:43038 · 2 productsBefore applying this update, make sure all previously released errata relevant to your system have been applied.

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • CISA-ADPSSVC decisionpoc2026-06-02
  • OpenCVESSVC decisionpoc—
  • NVDCVSS 3.18.1read 2026-10-23
  • CNACVSS 3.06.8read 2026-10-23
  • CNAweakness (CWE)CWE-23read 2026-10-23
  • FIRST EPSSEPSS score4.9 %2026-10-25
  • OSVaffected packages—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Published
2026-06-02
Last Modified
2026-07-22
NVD status
Analyzed

Frequently asked questions

What is CVE-2026-5422?

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.

Is CVE-2026-5422 actively exploited?

A proof-of-concept exploit exists for CVE-2026-5422, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2026-5422?

CVE-2026-5422 has a CVSS v3 base score of 8.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N.

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