Unrated severityNVD Advisory· Published Jun 27, 2026
Debian nbconvert: A vulnerability in jupyter/nbconvert versions <= 7.17.0 allows for Cross-site Sc…
CVE-2026-6658
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 `` 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.
Affected products
1Patches
Vulnerability mechanics
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