MediumFix available
libwebsockets — security advisory
Use After Free in WebSocket server implementation in lws_handshake_server in warmcat libwebsockets may allow an attacker, in specific configurations where the user provides a callback function that handles LWS_CALLBACK_HTTP_CONFIRM_UPGRADE, to achieve denial of service.
- Products
- libwebsockets
- Affected versions
- 4.1.6-3, 4.1.6-3.1, 4.3.2-1, 4.3.2-2, 4.3.2-3, 4.3.2-4, 4.3.3-1, 4.3.3-1.1, 4.3.3-1.1~exp1, 4.3.5-1, 4.3.5-2, 4.3.5-3, 4.3.5-4, 4.3.5-4.1, 4.3.5-5, 4.3.5-6, 4.3.5-7
- Fixed versions
- 4.3.5-1+deb13u1, 4.3.5-3
- CVEs
- CVE-2025-11677
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 28 Oct 2026, 11:09 UTC · Revision 1
Source evidence
Use After Free in WebSocket server implementation in lws_handshake_server in warmcat libwebsockets may allow an attacker, in specific configurations where the user provides a callback function that handles LWS_CALLBACK_HTTP_CONFIRM_UPGRADE, to achieve denial of service.
osv:DEBIAN-CVE-2025-11677
libwebsockets
Fixed versions: Not specified
libwebsockets
Fixed versions: 4.3.5-1+deb13u1
libwebsockets
Fixed versions: 4.3.5-3
Complete source record
{
"id": "5f6bc35bad460779bf5f0d507d8ce7f4670faa94786459d4e50a95f06f13b430",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2025-11677",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2025-11677",
"summary": "Use After Free in WebSocket server implementation in lws_handshake_server in warmcat libwebsockets may allow an attacker, in specific configurations where the user provides a callback function that handles LWS_CALLBACK_HTTP_CONFIRM_UPGRADE, to achieve denial of service.",
"evidence": "osv:DEBIAN-CVE-2025-11677",
"products": [
{
"name": {
"value": "libwebsockets",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "4.1.6-3",
"evidence": "/affected/0/versions"
},
{
"value": "4.1.6-3.1",
"evidence": "/affected/0/versions"
},
{
"value": "4.3.2-1",
"evidence": "/affected/0/versions"
},
{
"value": "4.3.2-2",
"evidence": "/affected/0/versions"
},
{
"value": "4.3.2-3",
"evidence": "/affected/0/versions"
},
{
"value": "4.3.2-4",
"evidence": "/affected/0/versions"
},
{
"value": "4.3.3-1",
"evidence": "/affected/0/versions"
},
{
"value": "4.3.3-1.1",
"evidence": "/affected/0/versions"
},
{
"value": "4.3.3-1.1~exp1",
"evidence": "/affected/0/versions"
},
{
"value": "4.3.5-1",
"evidence": "/affected/0/versions"
},
{
"value": "4.3.5-2",
"evidence": "/affected/0/versions"
},
{
"value": "4.3.5-3",
"evidence": "/affected/0/versions"
},
{
"value": "4.3.5-4",
"evidence": "/affected/0/versions"
},
{
"value": "4.3.5-4.1",
"evidence": "/affected/0/versions"
},
{
"value": "4.3.5-5",
"evidence": "/affected/0/versions"
},
{
"value": "4.3.5-6",
"evidence": "/affected/0/versions"
},
{
"value": "4.3.5-7",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
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"evidence": "/affected/1/package/name"
},
"prerequisites": [],
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{
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"evidence": "/affected/1/ranges"
}
],
"affected_versions": [
{
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"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "libwebsockets",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.3.5-3",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": [
{
"value": "4.3.5-1",
"evidence": "/affected/2/versions"
},
{
"value": "4.3.5-2",
"evidence": "/affected/2/versions"
}
]
}
],
"severity": "medium",
"structured": {
"id": "DEBIAN-CVE-2025-11677",
"aliases": [
"DEBIAN-CVE-2025-11677"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/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": "libwebsockets",
"purl": "pkg:deb/debian/libwebsockets?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
"4.1.6-3",
"4.1.6-3.1",
"4.3.2-1",
"4.3.2-2",
"4.3.2-3",
"4.3.2-4",
"4.3.3-1",
"4.3.3-1.1",
"4.3.3-1.1~exp1",
"4.3.5-1",
"4.3.5-2",
"4.3.5-3",
"4.3.5-4",
"4.3.5-4.1",
"4.3.5-5",
"4.3.5-6",
"4.3.5-7"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-11677.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.3.5-1+deb13u1"
}
]
}
],
"package": {
"name": "libwebsockets",
"purl": "pkg:deb/debian/libwebsockets?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"versions": [
"4.3.5-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-11677.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.3.5-3"
}
]
}
],
"package": {
"name": "libwebsockets",
"purl": "pkg:deb/debian/libwebsockets?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"4.3.5-1",
"4.3.5-2"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-11677.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-09T10:00:45.973305093Z",
"provider": "osv",
"upstream": [
"CVE-2025-11677"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2025-11677"
]
},
"related_cves": [
{
"value": "CVE-2025-11677",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 111735,
"published_at": "2025-10-20T14:15:39.357+00:00"
}