CVE-2026-6658

Published: Jun 26, 2026Modified: Jun 26, 2026Deferred

5.4

Vector

CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Exploitability: 2.3 / Impact: 2.7

Source: security@huntr.dev (Secondary)

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.

Related CWEs

CWE-79

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

References (2)

https://huntr.com/bounties/47570290-3b26-4477-8cfa-fdef7db5aefe

Source: security@huntr.dev

https://huntr.com/bounties/47570290-3b26-4477-8cfa-fdef7db5aefe

Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0

Timeline

No history available yet.