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CVE-2026-6658 Details

ANALYZED

This CVE record has been analyzed and enriched by NVDAPI.com as an independent party.

Description

A vulnerability in jupyter/nbconvert versions <= 7.17.0 allows for Cross-site Scripting (XSS) via unsanitized `text/vnd.mermaid` output in HTML exports. The `data_mermaid` block in `share/templates/lab/base.html.j2` renders `text/vnd.mermaid` cell output directly into HTML without escaping, enabling attackers to inject arbitrary HTML/JavaScript by breaking out of the `<pre>` tag. This vulnerability impacts any server using nbconvert to render notebooks as HTML, allowing attackers to execute arbitrary JavaScript in the context of users viewing the HTML export.

Metrics

CVSS 3.x Severity and Vector Strings:

VolerionCVSS-B:6.1 MEDIUMVector:CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CNA: [email protected]CVSS-B:5.4 MEDIUMVector:CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://huntr.com/bounties/47570290-3b26-4477-8cfa-fdef7db5aefe	CISA-ADP	ExploitTechnical Description
https://huntr.com/bounties/47570290-3b26-4477-8cfa-fdef7db5aefe	[email protected]	ExploitTechnical Description

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-79	Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')	[email protected]

Affected Products

Product	Versions
jupyter/nbconvert	<= 7.17.0 (semver)
CPE cpe:2.3:a:jupyter:nbconvert::::::python::* Remediation No remediation found in references.

Change History

2 change records found show changes

Date	Action	Recorded By
Jun 26, 2026	CVE Modified	CISA-ADP
Jun 26, 2026	New CVE Received	[email protected]