CVE-2026-39378
Medium
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.
SeverityMedium
CVSS6.5
Exploit probability—
ProductJupyter Nbconvert
PublishedApr 21, 2026
First seenApr 21, 2026
Weakness typeCWE-22Path traversalCWE-73CWE-73
How to fix
Update
- jupyter nbconvert7.17.1 or later
- nbconvert7.17.1 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| jupyter nbconvert | 6.5.0 ≤ v < 7.17.1 | 7.17.1 |
| nbconvertPyPI | 6.5.0 ≤ v < 7.17.1 | 7.17.1 |
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