CVE-2026-39377
nbconvert has an Arbitrary File Write via Path Traversal in Cell Attachment Filenames
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.
How to fix CVE-2026-39377
To remediate CVE-2026-39377, upgrade the affected package to a fixed version below.
- —no fix listed
- —upgrade to 7.17.1 or later
Is CVE-2026-39377 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (2)
- from 0
- >= 6.5.0, < 7.17.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM6.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N |