CVE-2026-114140: Jupyter nbconvert path traversal via output filename metadata

CVE-2026-114140 · Severity: high · CVSS 4 · Published 2026-10-21

Jupyter nbconvert is a tool that converts Jupyter notebooks to multiple document formats. A malicious notebook can exploit path traversal in output filenames to write attacker-controlled data to arbitrary locations on a victim's system when converted using certain exporters (markdown, LaTeX, reStructuredText, or AsciiDoc). This could allow an attacker to overwrite files or place malicious content where the victim can access it.

Technologies: Jupyter Nbconvert, nbconvert (PyPI). Vendors: Jupyter, PyPI.

Quick answers

Is CVE-2026-114140 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-114140 being exploited in the wild.
How severe is CVE-2026-114140?
High severity, with a CVSS score of 4, published 21 October 2026.
Which products and versions are affected?
Jupyter Nbconvert 5.4.0 to 7.17.1; nbconvert (PyPI) >= 5.4.0, <= 7.17.1, ECOSYSTEM:introduced=5.4.0,fixed=7.17.2.
Is there a fix for CVE-2026-114140?
Yes. nbconvert (PyPI): upgrade to 7.17.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-114140 attacked?
It is attacked with local access, in a software library.
Am I affected by CVE-2026-114140?
Check whether you run Jupyter Nbconvert or nbconvert (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • nbconvert (PyPI): upgrade to 7.17.2 or later
    pip install "nbconvert>=7.17.2"

Technical details

The ExtractOutputPreprocessor in nbconvert versions 5.4.0 through 7.17.1 fails to validate attacker-controlled cell output metadata filenames before joining them with the output directory path, enabling path traversal attacks. An attacker can craft a notebook with malicious output metadata containing path traversal sequences (e.g., "../../../") to write files outside the intended output directory. The vulnerability is triggered when a victim converts the notebook; simply running cells does not reproduce the malicious output metadata.

Affected products

  • Jupyter nbconvert 5.4.0 to 7.17.1

Identifiers

  • CVE-2026-114140
  • GHSA-pjvx-prjx-h659

Timeline

  • 2026-10-21: disclosed

References

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