nbconvert has an Arbitrary File Read via Path Traversal in HTMLExporter Image Embedding

GHSA-7jqv-fw35-gmx9 · CVE-2026-39378 · PYSEC-2026-2230

Published Apr 21, 2026 · Modified Sep 10, 2026

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Description

Summary

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.

Patches

Upgrade to nbconvert 7.17.1

Workarounds

Do not enable HTMLExporter.embed_images (it is not enabled by default).

References

WEB https://github.com/jupyter/nbconvert/security/advisories/GHSA-7jqv-fw35-gmx9
ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-39378
PACKAGE https://github.com/jupyter/nbconvert
WEB https://github.com/jupyter/nbconvert/releases/tag/v7.17.1

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