CVE-2026-44727

Fixed in a distro release EPSS <1%CVSS 9.3

Jupyter Server is the backend for Jupyter web applications. Prior to 2.20, the nbconvert HTTP handlers in jupyter_server render user-authored notebook HTML under the Jupyter origin without a sandbox directive in their Content-Security-Policy. Combined with nbconvert.HTMLExporter's default non-sanitizing behavior, a notebook carrying an HTML payload in a display_data output triggers stored XSS with cookie access, full /api/* authority, and kernel RCE. This vulnerability is fixed in 2.20.

Published 2026-06-22 · CVE record · OSV

Products: jupyter-server jupyter_server, Red Hat Migration Toolkit for Applications 8.2, Red Hat OpenShift AI 3.4, Red Hat OpenShift AI (RHOAI)

Fixed upstream

Distro releases