Path Traversal in Jupyter Nbconvert
CVE-2026-39378
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.
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:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.005 (37.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 37th percentile — 37.2% 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: 0.005 · change: +0.002
Affected products
- Jupyter Nbconvert — versions >= 6.5, < 7.17.1
Weakness classification (CWE)
References
- github.com/jupyter/nbconvert/security/advisories/GHSA-7jqv-fw35-gmx9 (Mitigation, Vendor Advisory)
- github.com/jupyter/nbconvert/releases/tag/v7.17.1 (Product)
Frequently asked questions
- What is CVE-2026-39378?
- CVE-2026-39378 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-2026-39378?
- Medium severity. CVSS v3 base score is 6.5 out of 10.