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.

The remote Fedora 43 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-275d2ecbbd advisory.

    New version fixing high-severity CVE.

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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. (CVE-2026-44727)

Note that Nessus relies on the presence of the package as reported by the vendor.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - 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. (CVE-2026-44727)

ID	Name	Product	Family	Severity
325213	Fedora 43 : python-jupyter-server (2026-275d2ecbbd)	Nessus	Fedora Local Security Checks	critical
322301	Linux Distros Unpatched Vulnerability : CVE-2026-44727	Nessus	Misc.	critical
443494	SCA: security update for jupyter-server (GHSA-fcw5-x6j4-ccmp)	Tenable Cloud Security	SCA Checks	critical
443494	SCA: security update for jupyter-server (GHSA-fcw5-x6j4-ccmp)	Tenable Self-Hosted Container Security	SCA Checks	critical

Detections

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CVE-2026-44727

critical

Tenable Plugins

critical

critical

critical

critical