jupyter-server — security advisory
Jupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, the secret used to sign authentication cookies is persisted to a static file at ~/.local/share/jupyter/runtime/jupyter_cookie_secret and is never rotated when a user changes their password. After a password reset and server restart, any previously issued authentication cookie remains cryptographically valid because the signing key has not changed. An attacker who has captured a session cookie through any means retains full authenticated access to the server regardless of subsequent password changes. This affects deployments using password-based authentication, particularly shared or public-facing servers where credential rotation is expected to revoke existing sessions. This issue has been fixed in version 2.18.0.
- Products
- jupyter-server
- Affected versions
- 1.13.1-1, 1.2.2-1, 1.23.3-1, 1.23.3-2, 2.14.2-5, 2.15.0-1, 2.17.0-1, 2.20.0-3
- Fixed versions
- Not specified
- CVEs
- CVE-2026-40934
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:10 UTC · Revision 1
Source evidence
Jupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, the secret used to sign authentication cookies is persisted to a static file at ~/.local/share/jupyter/runtime/jupyter_cookie_secret and is never rotated when a user changes their password. After a password reset and server restart, any previously issued authentication cookie remains cryptographically valid because the signing key has not changed. An attacker who has captured a session cookie through any means retains full authenticated access to the server regardless of subsequent password changes. This affects deployments using password-based authentication, particularly shared or public-facing servers where credential rotation is expected to revoke existing sessions. This issue has been fixed in version 2.18.0.
osv:UBUNTU-CVE-2026-40934
jupyter-server
Fixed versions: Not specified
jupyter-server
Fixed versions: Not specified
jupyter-server
Fixed versions: Not specified
jupyter-server
Fixed versions: Not specified
jupyter-server
Fixed versions: Not specified
Complete source record
{
"id": "908056530c556c0c63c8b434ed5ee6e854aed184679809fec599d62497cff74b",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-40934",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-40934",
"summary": "Jupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, the secret used to sign authentication cookies is persisted to a static file at ~/.local/share/jupyter/runtime/jupyter_cookie_secret and is never rotated when a user changes their password. After a password reset and server restart, any previously issued authentication cookie remains cryptographically valid because the signing key has not changed. An attacker who has captured a session cookie through any means retains full authenticated access to the server regardless of subsequent password changes. This affects deployments using password-based authentication, particularly shared or public-facing servers where credential rotation is expected to revoke existing sessions. This issue has been fixed in version 2.18.0.",
"evidence": "osv:UBUNTU-CVE-2026-40934",
"products": [
{
"name": {
"value": "jupyter-server",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.2.2-1",
"evidence": "/affected/0/versions"
},
{
"value": "1.13.1-1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "jupyter-server",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.23.3-1",
"evidence": "/affected/1/versions"
},
{
"value": "1.23.3-2",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "jupyter-server",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "2.14.2-5",
"evidence": "/affected/2/versions"
},
{
"value": "2.15.0-1",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "jupyter-server",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "2.17.0-1",
"evidence": "/affected/3/versions"
},
{
"value": "2.20.0-3",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "jupyter-server",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "2.15.0-1",
"evidence": "/affected/4/versions"
},
{
"value": "2.17.0-1",
"evidence": "/affected/4/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "UBUNTU-CVE-2026-40934",
"aliases": [
"UBUNTU-CVE-2026-40934"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N"
},
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "jupyter-server",
"purl": "pkg:deb/ubuntu/jupyter-server?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"1.2.2-1",
"1.13.1-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40934.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "jupyter-server",
"binary_version": "1.13.1-1"
},
{
"binary_name": "python3-jupyter-server",
"binary_version": "1.13.1-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
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],
"package": {
"name": "jupyter-server",
"purl": "pkg:deb/ubuntu/jupyter-server?arch=source&distro=noble",
"ecosystem": "Ubuntu:24.04:LTS"
},
"versions": [
"1.23.3-1",
"1.23.3-2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40934.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "jupyter-server",
"binary_version": "1.23.3-2"
},
{
"binary_name": "python3-jupyter-server",
"binary_version": "1.23.3-2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
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{
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}
],
"package": {
"name": "jupyter-server",
"purl": "pkg:deb/ubuntu/jupyter-server?arch=source&distro=questing",
"ecosystem": "Ubuntu:25.10"
},
"versions": [
"2.14.2-5",
"2.15.0-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40934.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "jupyter-server",
"binary_version": "2.15.0-1"
},
{
"binary_name": "python3-jupyter-server",
"binary_version": "2.15.0-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "jupyter-server",
"purl": "pkg:deb/ubuntu/jupyter-server?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"2.17.0-1",
"2.20.0-3"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40934.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "jupyter-server",
"binary_version": "2.20.0-3"
},
{
"binary_name": "python3-jupyter-server",
"binary_version": "2.20.0-3"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
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],
"package": {
"name": "jupyter-server",
"purl": "pkg:deb/ubuntu/jupyter-server?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"2.15.0-1",
"2.17.0-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40934.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "jupyter-server",
"binary_version": "2.17.0-1"
},
{
"binary_name": "python3-jupyter-server",
"binary_version": "2.17.0-1"
}
]
}
}
],
"modified": "2026-10-17T12:58:14.414094313Z",
"provider": "osv",
"upstream": [
"CVE-2026-40934"
],
"references": [
"https://ubuntu.com/security/CVE-2026-40934",
"https://www.cve.org/CVERecord?id=CVE-2026-40934",
"https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-5mrq-x3x5-8v8f"
]
},
"related_cves": [
{
"value": "CVE-2026-40934",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 358407,
"published_at": "2026-05-05T22:16:00+00:00"
}