CVE-2026-39378: The nbconvert tool, jupyter nbconvert, converts Jupyter notebooks to various other formats via Jinja templates

Q: How do I fix CVE-2026-39378?

nbconvert: upgrade to 7.17.1. Exact commands for each OS are on this page.

Q: Is CVE-2026-39378 being exploited?

CVE-2026-39378 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-39378 affect?

CVE-2026-39378 affects nbconvert. Severity is medium (CVSS 6.5). 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

Q: How urgent is CVE-2026-39378?

Priority 29/100. No elevated risk signals yet.

Routine

MEDIUM 6.5UPGRADE

CVE-2026-39378 is a medium-severity flaw (CVSS 6.5) affecting nbconvert. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.3% (top 77%)
CISA exploited list	No
Weakness	CWE-22, CWE-73
Published	2026-04-21
Last modified	2026-10-26

Publisher (CNA): GitHub, Inc. · Vendor: jupyter

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-21 01:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

jupyter nbconvert UPGRADE

Affected: >= 6.5.0 and < 7.17.1

Fixed in: 7.17.1

Safe to downgrade to: a release before 6.5.0

1. Check installed version

pip show nbconvert

2. UPGRADE to 7.17.1

pip install --upgrade "nbconvert>=7.17.1"

3. If no update is available yet, DOWNGRADE to a release before 6.5.0

pip index versions nbconvert pip install "nbconvert<6.5.0"

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-39378?

nbconvert: upgrade to 7.17.1. Exact commands for each OS are on this page.

Is CVE-2026-39378 being exploited?

CVE-2026-39378 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-39378 affect?

CVE-2026-39378 affects nbconvert. Severity is medium (CVSS 6.5). 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

How urgent is CVE-2026-39378?

Priority 29/100. No elevated risk signals yet.

Software pages

Jupyter vulnerabilities

Related CVEs

CVE-2026-39377 MEDIUM 6.5 UPGRADE The nbconvert tool, jupyter nbconvert, converts Jupyter notebooks to various other formats via Jinja templates

References

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