Path Traversal in Jupyter Nbconvert
CVE-2026-39377
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.
Vulnerability class: Path Traversal (Directory Traversal)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.004 (31.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 32nd percentile — 31.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.001
Affected products
- Jupyter Nbconvert — versions >= 6.5, < 7.17.1
Weakness classification (CWE)
References
- github.com/jupyter/nbconvert/security/advisories/GHSA-4c99-qj7h-p3vg (Mitigation, Vendor Advisory)
- github.com/jupyter/nbconvert/releases/tag/v7.17.1 (Product)
Frequently asked questions
- What is CVE-2026-39377?
- CVE-2026-39377 is a medium-severity vulnerability in Jupyter Nbconvert, classified under Path Traversal. CVSS score: 6.5/10. Published 2026-04-21.
- How severe is CVE-2026-39377?
- Medium severity. CVSS v3 base score is 6.5 out of 10.