CVE-2026-5422: A path traversal vulnerability exists in jupyter-server version 2.17.0 due to an incorrect root directory boun

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HIGH 8.1DOWNGRADE

CVE-2026-5422 is a high-severity flaw (CVSS 8.1) affecting jupyter server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

High severity
EPSS top 8%: very likely to be exploited
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	4.9% (top 8%)
CISA exploited list	No
Weakness	CWE-23
Published	2026-06-02
Last modified	2026-07-22

Publisher (CNA): huntr.dev · Vendor: jupyter

Last updated 2026-07-22 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-02 10:16 UTCPublished CVE record published
2026-07-22 19:10 UTCUpdated Record last modified

jupyter jupyter server DOWNGRADE

Affected: 2.17.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.17.0

1. Check installed version

apt-cache policy jupyter-server || rpm -q jupyter-server || jupyter-server --version

2. No fixed release: DOWNGRADE to a release before 2.17.0 (Debian / Ubuntu)

apt-cache madison jupyter-server sudo apt install jupyter-server=<VERSION_BEFORE_2.17.0> sudo apt-mark hold jupyter-server

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list jupyter-server sudo dnf downgrade jupyter-server-<VERSION_BEFORE_2.17.0> sudo dnf versionlock add jupyter-server

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Python (pip) · jupyter-server · FIXED · 2.18.2 · vulnerable: < 2.18.2 · source

pip install --upgrade "jupyter-server>=2.18.2" pip show jupyter-server

Fedora 46 · arm-none-eabi-binutils-cs · FIXED · 2.47-1.fc46 · FEDORA-2026-7498616952 · source

sudo dnf upgrade --advisory=FEDORA-2026-7498616952

Debian 12 · jupyter-server · NO FIX YET

Debian 13 · jupyter-server · NO FIX YET

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-5422?

jupyter server: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-5422 being exploited?

CVE-2026-5422 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-5422 affect?

CVE-2026-5422 affects jupyter server. Severity is high (CVSS 8.1). 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) witho

How urgent is CVE-2026-5422?

Priority 56/100. High severity; EPSS top 8%: very likely to be exploited; Public exploit reference

Software pages

Jupyter vulnerabilities

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References

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