CVE-2026-39378

Name of the Vulnerable Software and Affected Versions nbconvert versions 6.5 through 7.17.0

Description The nbconvert tool converts Jupyter notebooks to various formats using Jinja templates. When the HTMLExporter.embed images variable is set to True, the markdown renderer allows arbitrary file read through path traversal in image references. This allows a malicious notebook to exfiltrate sensitive files from the conversion host by embedding them as base64 data URIs in the output HTML.

Recommendations Update to version 7.17.1. As a temporary workaround, do not enable the HTMLExporter.embed images variable.