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CVE-2026-39377

nbconvert has an Arbitrary File Write via Path Traversal in Cell Attachment Filenames

Published: Apr 21, 2026Updated: Apr 23, 2026 Sources: CVE List NVDCWE-22
NVD MITRE
6.5CVSSMEDIUM
EPSS Score
0.3%
Top 82.2%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Workaround Only

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.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:RS:UC:NI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:RUser Interaction
Required
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:HIntegrity
High
A:NAvailability
None
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Weaknesses

CWE-22CWE-73

Affected Products

nbconvertjupyter
Mixed
AI / ML / notebook-mlops
jupyteross-projectAI / MLaka notebook, jupyter server, jupyterlab

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Workaround Available

MITRE ATT&CK

2 techniques
Collection
Discovery
View detailed technique mapping

References

https://github.com/jupyter/nbconvert/releases/tag/v7.17.1
github.com
https://github.com/jupyter/nbconvert/security/advisories/GHSA-4c99-qj7h-p3vg
github.com

Timeline

Published
Apr 21, 2026
Last Updated
Apr 23, 2026

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