VDB
CVE-2026-44727
CVE-2026-44727
PUBLISHED
CVSS 9.3 CRITICAL
Reported by GitHub_M · Published June 22, 2026
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.
Risk Scores
CVSS 4.0
9.3
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| jupyter-server | jupyter_server | < 2.20 |
| Red Hat | Red Hat OpenShift AI (RHOAI) | |
| jupyter-server | jupyter_server | < 2.20, < 2.20, < 2.20 |
| Red Hat | Red Hat OpenShift AI 3.4 | 1787073546, 1787073546 |
| Red Hat | Red Hat OpenShift AI 3.4 | 1787077779, 1787077779 |
| Red Hat | Red Hat OpenShift AI 3.4 | 1787076778, 1787076778 |
| Red Hat | Red Hat OpenShift AI 3.4 | 1787074078, 1787074078 |
| Red Hat | Red Hat OpenShift AI 3.4 | 1787073713, 1787073713 |
| Red Hat | Red Hat OpenShift AI (RHOAI) | |
| Red Hat | Red Hat OpenShift AI 3.4 | 1787073717, 1787073717 |
| Red Hat | Red Hat OpenShift AI (RHOAI) | |
| Red Hat | Red Hat OpenShift AI 3.4 | 1787073605, 1787073605 |
| Red Hat | Red Hat OpenShift AI 3.4 | 1787073929, 1787073929 |
| Red Hat | Red Hat OpenShift AI (RHOAI) | |
| Red Hat | Migration Toolkit for Applications 8 | |
| chainguard | tensorflow-cpu-jupyter | 0, 0, 0 |
| Red Hat | Red Hat OpenShift AI (RHOAI) | |
| Red Hat | Red Hat OpenShift AI 3.4 | 1787073593, 1787073593 |
| Red Hat | Red Hat OpenShift AI (RHOAI) | |
| Red Hat | Red Hat OpenShift AI (RHOAI) |
…and 17 more
Timeline
- Jun 18, 2026 CVE Published
- Jun 23, 2026 Coalition ESS Score
- Jun 23, 2026 Security Advisory
- Aug 7, 2026 EPSS Score
- Aug 14, 2026 Distribution Patch
- Aug 14, 2026 Security Advisory
- Aug 24, 2026 EPSS Score
- Aug 26, 2026 EPSS Score
- Aug 28, 2026 CVE Updated
- Aug 28, 2026 Distribution Patch
- Aug 30, 2026 EPSS Score
- Sep 3, 2026 EPSS Score
References
- https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-fcw5-x6j4-ccmp x_refsource_CONFIRM
- https://github.com/jupyter-server/jupyter_server/commit/6cbee8d65e71abac851c4492fea987ad080580bd x_refsource_MISC
- https://access.redhat.com/security/cve/CVE-2026-44727 vdb
- RHBZ#2491516 issue
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-44727.json url
- https://access.redhat.com/errata/RHSA-2026:43038 vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:60520 vendor-advisory
- https://nvd.nist.gov/vuln/detail/CVE-2026-44727 advisory
- https://github.com/advisories/GHSA-fcw5-x6j4-ccmp advisory
- https://github.com/jupyter-server/jupyter_server url
- https://github.com/pypa/advisory-database/tree/main/vulns/jupyter-server/PYSEC-2026-366.yaml advisory
- https://pypi.org/project/jupyter-server url