How severe is CVE-2023-40170?

CVE-2023-40170 has a CVSS score of 4.6/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2023-40170?

CVE-2023-40170 affects the following packages: jupyter-server (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2023-40170?

Update jupyter-server to 2.7.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-40170 is resolved across your whole dependency graph.

How do I detect CVE-2023-40170 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jupyter-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2023-40170 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2023-40170 actively exploited in the wild?

No public exploit code has been indexed for CVE-2023-40170 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2023-40170?

CVE-2023-40170 has an EPSS (Exploit Prediction Scoring System) score of 0.6%, placing it in the 50th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2023-40170?

CVE-2023-40170 is classified as CWE-284 (CWE-284), Missing Authentication (CWE-306), Cross-site Scripting (XSS) (CWE-79). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2023-40170 published, and has it been updated?

CVE-2023-40170 was published on August 28, 2023 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍

🐍 PyPI

Not in CISA KEV

MEDIUM severity

CVE-2023-40170 — jupyter-server

MEDIUMFix: jupyter-server/jupyter_server@87a4927

CVE-2023-40170 is a medium-severity (CVSS 4.6) CWE-284 vulnerability in jupyter-server. A fix is available for jupyter-server — see the affected versions and patch details below.

cross-site inclusion (XSSI) of files in jupyter-server

Also known asGHSA-64x5-55rw-9974PYSEC-2023-157

Published

Aug 28, 2023

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2023-40170.

EPSS Exploitation Probability

via FIRST.org ↗

0.6%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs50th percentile — riskier than 50% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐍jupyter-server

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Impact

Improper cross-site credential checks on /files/ URLs could allow exposure of certain file contents, or accessing files when opening untrusted files via "Open image in new tab".

Patches

Jupyter Server 2.7.2

Workarounds

Use lower performance --ContentsManager.files_handler_class=jupyter_server.files.handlers.FilesHandler, which implements the correct checks.

References

Upstream patch for CVE-2019-9644 was not applied completely, leaving part of the vulnerability open.

Vulnerability reported by Tim Coen via the bug bounty program sponsored by the European Commission and hosted on the Intigriti platform.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`jupyter-server`	all versions	2.7.2`pip install --upgrade 'jupyter-server==2.7.2'`

Affected Products

1 product · 1 configurations

Application

jupyter serverjupyter

< 2.7.2

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jupyter-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update jupyter-server to 2.7.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-40170 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

### Impact Improper cross-site credential checks on `/files/` URLs could allow exposure of certain file contents, or accessing files when opening untrusted files via "Open image in new tab". ### Patches Jupyter Server 2.7.2 ### Workarounds Use lower performance `--ContentsManager.files_handler_class=jupyter_server.files.handlers.FilesHandler`, which implements the correct checks. ### References Upstream patch for CVE-2019-9644 was not applied completely, leaving part of the vulnerability open. Vulnerability reported by Tim Coen via the [bug bounty program](https://app.intigriti.com/pr

O3 Security · Impact-Aware SCA

Is CVE-2023-40170 in your dependencies?

Find it across PyPI, including transitive dependencies.

Scan my dependencies How O3 SCA works