CVE-2026-39378
6.5 · MEDIUMOverview
CVE-2026-39378 is a medium-severity vulnerability affecting jupyter nbconvert. It was published on April 21, 2026 and has a CVSS 3.1 base score of 6.5 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 6.5, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
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.
Remediation
Check the references section for vendor advisories and patches from jupyter. Update nbconvert to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| jupyter | nbconvert | >= 6.5.0, < 7.17.1 | Affected |
Frequently Asked Questions
What is CVE-2026-39378?
CVE-2026-39378 is a medium-severity vulnerability affecting jupyter nbconvert. It was published on April 21, 2026 and has a CVSS 3.1 base score of 6.5 (MEDIUM).
How severe is CVE-2026-39378?
This vulnerability has a CVSS 3.1 base score of 6.5, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-39378?
Check the references section for vendor advisories and patches from jupyter. Update nbconvert to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-39378?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-39378 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
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