Critical9.0Vendor: HighRed Hat Linux

Critical [CVE-2026-44727] Remote Code Execution via stored Cross-Site Scripting in nbconvert handlers

This critical-severity Red Hat Linux advisory covers CVE-2026-44727 affecting Red Hat Migration Toolkit for Applications 8.2, Red Hat OpenShift AI (RHOAI).

CVE-2026-44727 Published Jun 22, 2026Updated by vendor Jun 22, 2026

CVE-2026-44727

Affected products & platforms

Red Hat LinuxUnclassified

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Summary

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.

A flaw was found in Jupyter Server. A remote attacker could exploit this to gain cookie access, full API authority, and achieve kernel Remote Code Execution (RCE).

Red Hat severity: Important — CVSS 9 (CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H). Weakness: CWE-79.

Affected Red Hat products: Red Hat Migration Toolkit for Applications 8.2; Red Hat OpenShift AI (RHOAI). Red Hat lists Red Hat OpenShift AI (RHOAI) as not affected.

Red Hat fixing advisory: RHSA-2026:43038.

Affected versions

< 2.20

Official advisory · high-confidence parse· fetched 6 days ago·verify at source

Fixed versions

2.20
mta/mta-solution-server-rhel9:1784109883
RHSA-2026:43038

Official advisory · high-confidence parse· fetched 6 days ago·verify at source

Mitigation

Upgrade to a fixed release: 2.20, mta/mta-solution-server-rhel9:1784109883, RHSA-2026:43038. That is the remediation for this advisory.

The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.

Official advisory · high-confidence parse· fetched 6 days ago·verify at source

Sources

Official and corroborating records used to build this advisory.

Red Hat Security Data APIofficial
Official vendor source used to discover this advisory; it remains the authority for affected products and remediation. Discovered from the machine-readable feed https://access.redhat.com/hydra/rest/securitydata/cve.json; this link opens the Red Hat Linux advisory index instead of the raw feed document.
Red Hat Linux
Official vendor advisoryofficial
Official advisory page fetched and parsed; accepted detail fields are attributed to this page.
Red Hat Linux
CVE.org CNA affected-product recordCVE.org
Structured CNA affected[] data independently confirmed the affected product scope; native advisory content remains authoritative.
CVE Program

Cross-references

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CVE-2026-44727NVD CVE.org MITRE

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