CVE-2026-6658
Cross-site Scripting (XSS) in jupyter/nbconvert
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.
INFO
Published Date :
June 26, 2026, 9:40 a.m.
Last Modified :
June 26, 2026, 9:40 a.m.
Remotely Exploit :
Yes !
Source :
@huntr_ai
Affected Products
The following products are affected by CVE-2026-6658
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.0 | MEDIUM | MITRE-CVE |
Solution
- Update jupyter/nbconvert to a patched version.
- Ensure mermaid output is properly sanitized.
- Review security configurations for HTML exports.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-6658 vulnerability anywhere in the article.