Description
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.
References
- www.cve.org/CVERecord ↗
- nvd.nist.gov/vuln/detail/CVE-2026-44727 ↗
- github.com/jupyter-server/jupyter_server/commit/6cbee8d65e71abac851c4492fea987ad080580bd ↗
- github.com/jupyter-server/jupyter_server/security/advisories/GHSA-fcw5-x6j4-ccmp ↗
- access.redhat.com/errata/RHSA-2026:43038 ↗
- access.redhat.com/errata/RHSA-2026:60520 ↗
- access.redhat.com/security/cve/CVE-2026-44727 ↗
- bugzilla.redhat.com/show_bug.cgi ↗
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-44727.json ↗
Related CVEs
← CVE Index: search every CVE from the last 30 days
This product uses the NVD API but is not endorsed or certified by the NVD. CVSS scores do not establish exploitation.