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

Source: https://junglewise.ai/threats/cve-2026-114140-the-nbconvert-tool-jupyter-nbconvert-converts-jupyter-notebooks  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-21. Updated: 2026-10-21  
License: CC BY 4.0 with a link back

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](https://junglewise.ai/threats/technologies/jupyter-nbconvert), [nbconvert (PyPI)](https://junglewise.ai/threats/technologies/nbconvert). Vendors: [Jupyter](https://junglewise.ai/threats/vendors/jupyter), [PyPI](https://junglewise.ai/threats/vendors/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

  ```sh
  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

- [https://github.com/jupyter/nbconvert/commit/ce4bd99aec31d81d759fa8eeb8643179392ec66f](https://github.com/jupyter/nbconvert/commit/ce4bd99aec31d81d759fa8eeb8643179392ec66f)
- [https://github.com/jupyter/nbconvert/releases/tag/v7.17.2](https://github.com/jupyter/nbconvert/releases/tag/v7.17.2)

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- [nbconvert has an Arbitrary File Write via Path Traversal in Cell Attachment Filenames](https://junglewise.ai/threats/cve-2026-39377-nbconvert-has-an-arbitrary-file-write-via-path-traversal-in-cell)
- [nbconvert vulnerable to cross-site scripting (XSS) via multiple exploit paths](https://junglewise.ai/threats/cve-2021-32862-nbconvert-vulnerable-to-cross-site-scripting-xss-via-multiple)