Medium
python-tornado — security advisory
Tornado before 6.5.8 contains an incomplete fix for cookie attribute injection that allows attackers to inject arbitrary cookie attributes by passing capitalized or legacy keyword arguments to set_cookie. Attackers can embed semicolon-delimited data in capitalized parameters like Domain, Path, or SameSite to bypass validation and modify cookie security attributes.
- Products
- python-tornado
- Affected versions
- 6.2.0-3, 6.2.0-3+deb12u1, 6.2.0-3+deb12u2, 6.2.0-3+deb12u3, 6.2.0-3+deb12u4, 6.3.2-1, 6.4.0-1, 6.4.0-2, 6.4.1-1, 6.4.1-2, 6.4.1-3, 6.4.2-1, 6.4.2-2, 6.4.2-3, 6.5.2-1, 6.5.2-2, 6.5.2-3, 6.5.4-0.1, 6.5.4-1, 6.5.5-1, 6.5.5-2, 6.5.5-3, 6.5.5-4, 6.5.5-5
- Fixed versions
- Not specified
- CVEs
- CVE-2026-91991
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 28 Oct 2026, 11:06 UTC · Revision 1
Source evidence
Tornado before 6.5.8 contains an incomplete fix for cookie attribute injection that allows attackers to inject arbitrary cookie attributes by passing capitalized or legacy keyword arguments to set_cookie. Attackers can embed semicolon-delimited data in capitalized parameters like Domain, Path, or SameSite to bypass validation and modify cookie security attributes.
osv:DEBIAN-CVE-2026-91991
python-tornado
Fixed versions: Not specified
python-tornado
Fixed versions: Not specified
Complete source record
{
"id": "ef60a3ccfaca161e187d0103e81fc4f8268a22c44a328173f737ed64efa635dc",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-91991",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2026-91991",
"summary": "Tornado before 6.5.8 contains an incomplete fix for cookie attribute injection that allows attackers to inject arbitrary cookie attributes by passing capitalized or legacy keyword arguments to set_cookie. Attackers can embed semicolon-delimited data in capitalized parameters like Domain, Path, or SameSite to bypass validation and modify cookie security attributes.",
"evidence": "osv:DEBIAN-CVE-2026-91991",
"products": [
{
"name": {
"value": "python-tornado",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "6.2.0-3",
"evidence": "/affected/0/versions"
},
{
"value": "6.2.0-3+deb12u1",
"evidence": "/affected/0/versions"
},
{
"value": "6.2.0-3+deb12u2",
"evidence": "/affected/0/versions"
},
{
"value": "6.2.0-3+deb12u3",
"evidence": "/affected/0/versions"
},
{
"value": "6.2.0-3+deb12u4",
"evidence": "/affected/0/versions"
},
{
"value": "6.3.2-1",
"evidence": "/affected/0/versions"
},
{
"value": "6.4.0-1",
"evidence": "/affected/0/versions"
},
{
"value": "6.4.0-2",
"evidence": "/affected/0/versions"
},
{
"value": "6.4.1-1",
"evidence": "/affected/0/versions"
},
{
"value": "6.4.1-2",
"evidence": "/affected/0/versions"
},
{
"value": "6.4.1-3",
"evidence": "/affected/0/versions"
},
{
"value": "6.4.2-1",
"evidence": "/affected/0/versions"
},
{
"value": "6.4.2-2",
"evidence": "/affected/0/versions"
},
{
"value": "6.4.2-3",
"evidence": "/affected/0/versions"
},
{
"value": "6.5.2-1",
"evidence": "/affected/0/versions"
},
{
"value": "6.5.2-2",
"evidence": "/affected/0/versions"
},
{
"value": "6.5.2-3",
"evidence": "/affected/0/versions"
},
{
"value": "6.5.4-0.1",
"evidence": "/affected/0/versions"
},
{
"value": "6.5.4-1",
"evidence": "/affected/0/versions"
},
{
"value": "6.5.5-1",
"evidence": "/affected/0/versions"
},
{
"value": "6.5.5-2",
"evidence": "/affected/0/versions"
},
{
"value": "6.5.5-3",
"evidence": "/affected/0/versions"
},
{
"value": "6.5.5-4",
"evidence": "/affected/0/versions"
},
{
"value": "6.5.5-5",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "python-tornado",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "6.4.2-3",
"evidence": "/affected/1/versions"
},
{
"value": "6.5.2-1",
"evidence": "/affected/1/versions"
},
{
"value": "6.5.2-2",
"evidence": "/affected/1/versions"
},
{
"value": "6.5.2-3",
"evidence": "/affected/1/versions"
},
{
"value": "6.5.4-0.1",
"evidence": "/affected/1/versions"
},
{
"value": "6.5.4-1",
"evidence": "/affected/1/versions"
},
{
"value": "6.5.5-1",
"evidence": "/affected/1/versions"
},
{
"value": "6.5.5-2",
"evidence": "/affected/1/versions"
},
{
"value": "6.5.5-3",
"evidence": "/affected/1/versions"
},
{
"value": "6.5.5-4",
"evidence": "/affected/1/versions"
},
{
"value": "6.5.5-5",
"evidence": "/affected/1/versions"
}
]
}
],
"severity": "medium",
"structured": {
"id": "DEBIAN-CVE-2026-91991",
"aliases": [
"DEBIAN-CVE-2026-91991"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "python-tornado",
"purl": "pkg:deb/debian/python-tornado?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
"6.2.0-3",
"6.2.0-3+deb12u1",
"6.2.0-3+deb12u2",
"6.2.0-3+deb12u3",
"6.2.0-3+deb12u4",
"6.3.2-1",
"6.4.0-1",
"6.4.0-2",
"6.4.1-1",
"6.4.1-2",
"6.4.1-3",
"6.4.2-1",
"6.4.2-2",
"6.4.2-3",
"6.5.2-1",
"6.5.2-2",
"6.5.2-3",
"6.5.4-0.1",
"6.5.4-1",
"6.5.5-1",
"6.5.5-2",
"6.5.5-3",
"6.5.5-4",
"6.5.5-5"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-91991.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "python-tornado",
"purl": "pkg:deb/debian/python-tornado?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"6.4.2-3",
"6.5.2-1",
"6.5.2-2",
"6.5.2-3",
"6.5.4-0.1",
"6.5.4-1",
"6.5.5-1",
"6.5.5-2",
"6.5.5-3",
"6.5.5-4",
"6.5.5-5"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-91991.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-09T09:47:23.280507117Z",
"provider": "osv",
"upstream": [
"CVE-2026-91991"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2026-91991"
]
},
"related_cves": [
{
"value": "CVE-2026-91991",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 111433,
"published_at": "2026-09-15T16:17:58.293+00:00"
}