MediumFix available
jupyter-server — security advisory
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.
- Products
- jupyter-server
- Affected versions
- 1.23.3-1, 1.23.3-2, 2.14.0-1, 2.14.2-1, 2.14.2-2, 2.14.2-3, 2.14.2-4, 2.14.2-5, 2.15.0-1, 2.17.0-1, 2.20.0-1, 2.20.0-2, 2.20.0-3, 2.9.1-1
- Fixed versions
- 2.20.0-1
- CVEs
- CVE-2026-44727
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 12:16 UTC · Revision 2
Source evidence
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.
osv:DEBIAN-CVE-2026-44727
jupyter-server
Fixed versions: Not specified
jupyter-server
Fixed versions: Not specified
jupyter-server
Fixed versions: 2.20.0-1
Complete source record
{
"id": "f2df423c24097a5e194925837239c8d40a5544a17cd676623d20f601aedf7167",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-44727",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2026-44727",
"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.",
"evidence": "osv:DEBIAN-CVE-2026-44727",
"products": [
{
"name": {
"value": "jupyter-server",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.23.3-1",
"evidence": "/affected/0/versions"
},
{
"value": "1.23.3-2",
"evidence": "/affected/0/versions"
},
{
"value": "2.14.0-1",
"evidence": "/affected/0/versions"
},
{
"value": "2.14.2-1",
"evidence": "/affected/0/versions"
},
{
"value": "2.14.2-2",
"evidence": "/affected/0/versions"
},
{
"value": "2.14.2-3",
"evidence": "/affected/0/versions"
},
{
"value": "2.14.2-4",
"evidence": "/affected/0/versions"
},
{
"value": "2.14.2-5",
"evidence": "/affected/0/versions"
},
{
"value": "2.15.0-1",
"evidence": "/affected/0/versions"
},
{
"value": "2.17.0-1",
"evidence": "/affected/0/versions"
},
{
"value": "2.20.0-1",
"evidence": "/affected/0/versions"
},
{
"value": "2.20.0-2",
"evidence": "/affected/0/versions"
},
{
"value": "2.20.0-3",
"evidence": "/affected/0/versions"
},
{
"value": "2.9.1-1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "jupyter-server",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "2.15.0-1",
"evidence": "/affected/1/versions"
},
{
"value": "2.17.0-1",
"evidence": "/affected/1/versions"
},
{
"value": "2.20.0-1",
"evidence": "/affected/1/versions"
},
{
"value": "2.20.0-2",
"evidence": "/affected/1/versions"
},
{
"value": "2.20.0-3",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "jupyter-server",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "2.20.0-1",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": [
{
"value": "2.15.0-1",
"evidence": "/affected/2/versions"
},
{
"value": "2.17.0-1",
"evidence": "/affected/2/versions"
}
]
}
],
"severity": "medium",
"structured": {
"id": "DEBIAN-CVE-2026-44727",
"aliases": [
"DEBIAN-CVE-2026-44727"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "jupyter-server",
"purl": "pkg:deb/debian/jupyter-server?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
"1.23.3-1",
"1.23.3-2",
"2.14.0-1",
"2.14.2-1",
"2.14.2-2",
"2.14.2-3",
"2.14.2-4",
"2.14.2-5",
"2.15.0-1",
"2.17.0-1",
"2.20.0-1",
"2.20.0-2",
"2.20.0-3",
"2.9.1-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-44727.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "jupyter-server",
"purl": "pkg:deb/debian/jupyter-server?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"versions": [
"2.15.0-1",
"2.17.0-1",
"2.20.0-1",
"2.20.0-2",
"2.20.0-3"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-44727.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "2.20.0-1"
}
]
}
],
"package": {
"name": "jupyter-server",
"purl": "pkg:deb/debian/jupyter-server?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"2.15.0-1",
"2.17.0-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-44727.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-26T11:47:33.241471944Z",
"provider": "osv",
"upstream": [
"CVE-2026-44727"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2026-44727"
]
},
"related_cves": [
{
"value": "CVE-2026-44727",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 450754,
"published_at": "2026-06-22T21:16:24.26+00:00"
}