Medium severity · published Apr 21, 2026
CVE-2026-39378
nbconvert has an Arbitrary File Read via Path Traversal in HTMLExporter Image Embedding
6.5
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
High
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 23% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NB
nbconvert · jupyter
>= 6.5, < 7.17.1 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-39378
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-39378
Product
https://github.com/jupyter/nbconvert/releases/tag/v7.17.1
Mitigation
https://github.com/jupyter/nbconvert/security/advisories/GHSA-7jqv-fw35-gmx9
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