What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-21 · updated 2026-10-26
• Weakness: CWE-22

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.

Affected products

• jupyter nbconvert: from 6.5.0 before 7.17.1 — fixed in 7.17.1

How to fix

Upgrade to a fixed version: jupyter nbconvert 7.17.1. Check the vendor advisory for mitigations.

References

• https://github.com/jupyter/nbconvert/releases/tag/v7.17.1
• https://github.com/jupyter/nbconvert/security/advisories/GHSA-7jqv-fw35-gmx9

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