CVE-2026-39378 — MEDIUM (CVSS 6.5) AI Security Vulnerability

Q: What is CVE-2026-39378?

nbconvert has an Arbitrary File Read via Path Traversal in HTMLExporter Image Embedding

Q: Is CVE-2026-39378 actively exploited?

No confirmed active exploitation of CVE-2026-39378 has been reported, but organizations should still patch proactively.

Q: How to fix CVE-2026-39378?

Update to patched version: nbconvert 7.17.1.

Q: What is the CVSS score for CVE-2026-39378?

CVE-2026-39378 has a CVSS v3.1 base score of 6.5 (MEDIUM).

## Summary 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. ## Patches...

Full CISO analysis pending enrichment.

Affected Systems

Package	Ecosystem	Vulnerable Range	Patched
nbconvert	pip	>= 6.5.0, < 7.17.1	`7.17.1`
13.1K OpenSSF 4.7 2.9K dependents Pushed 5d ago 100% patched ~813d to patch Full package profile →

Do you use nbconvert? You're affected.

Severity & Risk

CVSS 3.1

6.5 / 10

EPSS

N/A

Exploitation Status

No known exploitation

Sophistication

N/A

Attack Surface

AV Network

AC Low

PR None

UI Required

S Unchanged

C High

I None

A None

Recommended Action

Patch available

Update nbconvert to version 7.17.1

Compliance Impact

Compliance analysis pending. Sign in for full compliance mapping when available.

Frequently Asked Questions

What is CVE-2026-39378?

nbconvert has an Arbitrary File Read via Path Traversal in HTMLExporter Image Embedding

Is CVE-2026-39378 actively exploited?

No confirmed active exploitation of CVE-2026-39378 has been reported, but organizations should still patch proactively.

How to fix CVE-2026-39378?

Update to patched version: nbconvert 7.17.1.

What is the CVSS score for CVE-2026-39378?

CVE-2026-39378 has a CVSS v3.1 base score of 6.5 (MEDIUM).

Technical Details

NVD Description

## Summary 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. ## Patches Upgrade to nbconvert 7.17.1 ## Workarounds Do not enable `HTMLExporter.embed_images` (it is not enabled by default).