{"id":"UBUNTU-CVE-2026-44727","details":"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.","modified":"2026-06-30T18:18:15.456451927Z","published":"2026-06-22T21:16:00Z","upstream":["CVE-2026-44727"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-44727"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-44727"},{"type":"REPORT","url":"https://github.com/jupyter-server/jupyter_server/commit/6cbee8d65e71abac851c4492fea987ad080580bd"},{"type":"REPORT","url":"https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-fcw5-x6j4-ccmp"}],"affected":[{"package":{"name":"jupyter-server","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/jupyter-server?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.2-1","1.13.1-1"],"ecosystem_specific":{"binaries":[{"binary_name":"jupyter-server","binary_version":"1.13.1-1"},{"binary_name":"python3-jupyter-server","binary_version":"1.13.1-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44727.json"}},{"package":{"name":"jupyter-server","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/jupyter-server?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.23.3-1","1.23.3-2"],"ecosystem_specific":{"binaries":[{"binary_version":"1.23.3-2","binary_name":"jupyter-server"},{"binary_name":"python3-jupyter-server","binary_version":"1.23.3-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44727.json"}},{"package":{"name":"jupyter-server","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/jupyter-server?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.14.2-5","2.15.0-1"],"ecosystem_specific":{"binaries":[{"binary_name":"jupyter-server","binary_version":"2.15.0-1"},{"binary_name":"python3-jupyter-server","binary_version":"2.15.0-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44727.json"}},{"package":{"name":"jupyter-server","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/jupyter-server?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.15.0-1","2.17.0-1"],"ecosystem_specific":{"binaries":[{"binary_version":"2.17.0-1","binary_name":"jupyter-server"},{"binary_version":"2.17.0-1","binary_name":"python3-jupyter-server"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44727.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"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"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N"},{"type":"Ubuntu","score":"medium"}]}