CVE-2026-6658
Cross-site Scripting (XSS) in jupyter/nbconvert
Vexday Risk Score
13Low
SSVC decision (CISA)
Track
No exploitation signal → monitor
CVSS 5.4EPSS 0.1%KEV nãoPoC —Nuclei —Metasploit —Patch —
Lifecycle
26 Jun 2026Published on NVD
Recommendation: Monitor — no exploitation signal at the moment.
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.
CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Affected products
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