CVE-2026-39377

nbconvert has an Arbitrary File Write via Path Traversal in Cell Attachment Filenames

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. Versions 6.5 through 7.17.0 allow arbitrary file writes to locations outside the intended output directory when processing notebooks containing crafted cell attachment filenames. The `ExtractAttachmentsPreprocessor` passes attachment filenames directly to the filesystem without sanitization, enabling path traversal attacks. This vulnerability provides complete control over both the destination path and file extension. Version 7.17.1 contains a patch.

Scores

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