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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 21, 2026 Sources: CVE List NVD
NVD MITRE
6.5CVSS
MEDIUM

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.

EPSS Score
N/A
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available

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

Weaknesses

CWE-22CWE-73

Affected Products

nbconvert
jupyter

Attack Graph

Products CVE Techniques Tactics

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Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

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 21, 2026

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