PT-2026-52688 · Nbconvert · Nconvert

Published 2026-06-26 · Updated 2026-06-26 · CVE-2026-6658

Positive Technologies (AI Summary)

CVSS v3.1

5.4

Medium

Base vector

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

Name of the Vulnerable Software and Affected Versions nbconvert versions prior to 7.17.1

Description An issue exists where text/vnd.mermaid output in HTML exports is not properly sanitized. Specifically, the data mermaid block in share/templates/lab/base.html.j2 renders this output directly into HTML without escaping. This allows an attacker to break out of the <pre> tag and inject arbitrary HTML or JavaScript, which is then executed in the context of users viewing the exported HTML file.

Recommendations Update nbconvert to a version later than 7.17.0.

Exploit

Fix

XSS

Weakness Enumeration

CWE-79

Related Identifiers

CVE-2026-6658

Affected Products

Nconvert

References · 3

• 🔥 https://huntr.com/bounties/47570290-3b26-4477-8cfa-fdef7db5aefe · Exploit
• https://nvd.nist.gov/vuln/detail/CVE-2026-6658 · Security Note
• https://twitter.com/VulmonFeeds/status/2070457595899355243 · Twitter Post