CVE-2026-6658
Last modified
CVE-2026-6658 is a medium-severity vulnerability rated 5.4/10 on the CVSS scale. 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. EPSS estimates a 0.23% chance of exploitation in the next 30 days.
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:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Weakness Enumeration
References
Timeline
- Published
- Last Modified
- Status
- Deferred
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