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CVE-2026-44727

9.3 critical SSVC exploitation: none Modified
NVD · CVE.org

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.

Fix

Patch, vendor advisory and mitigation references on NVD 2

Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.

Change history 1

  1. First seenCVSS 9.3 · jupyterNVD modified 2026-10-25 23:10

Affected (CPE criteria) 1

  • cpe:2.3:a:jupyter:jupyter_server:*:*:*:*:*:*:*:*

References 7