# CVE-2026-39377

> Vulnerability · severity: **MEDIUM** (CVSS 6.5).

## 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.

## Key facts

- **CVE ID:** CVE-2026-39377
- **Published:** 2026-04-21
- **CVSS severity:** MEDIUM
- **CVSS base score:** 6.5
- **CWE codes:** CWE-22, CWE-73

## Affected products

- `jupyter:nbconvert`

## Primary sources

- NIST NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-39377

## Citation

> AI Analytics. CVE-2026-39377. Retrieved 2026-07-23 from https://api.ai-analytics.org/cve/CVE-2026-39377. Derived from NIST NVD. Licensed CC0.

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