CVE-2026-39378

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

State: Published
Severity: 6.5 Medium
Published: Apr 21, 2026
Updated: Apr 21, 2026
Reserved: Apr 6, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	6.5 Medium	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N	GitHub_M

Weaknesses

CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CWE-73 External Control of File Name or Path

Affected Products

Product	Versions
nbconvertjupyter	>= 6.5, < 7.17.1Affected

References

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