CVE-2026-6658
Cross-site Scripting (XSS) in jupyter/nbconvert
- Published
- Updated
- Reserved
- Assigned by
- @huntr_ai
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| @huntr_aiCNA (assigner) | 3.0 | Medium5.4 | CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N |
| NVDNVD · Deferred | 3.0 | Medium5.4 | CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N |
- EPSS (exploitation in 30 days)
- 0.16% · top 95% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: poc · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.4.
Weakness
Affected products
- affected unspecified – ≤ latest
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- PyPInbconvertGHSA-9754-6rhw-gj3h (opens in a new tab)
References (1)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-9754-6rhw-gj3h (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-6658)Record last updated .