CriticalFix available
libwebsockets — security advisory
libwebsockets HTTP/2 HPACK Path Header Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of libwebsockets. Authentication is not required to exploit this vulnerability. The specific flaw exists within the parsing of HTTP/2 HPACK path header. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of an allocated buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-31036.
- Products
- libwebsockets
- Affected versions
- 1.2.2-1, 1.6.0-3, 1.6.0-4, 1.6.0-5, 1.6.1-1, 1.7.0-1ubuntu1, 1.7.0-2, 1.7.1-1, 2.0.3-3, 2.0.3-3build1, 3.2.1-3, 3.2.1-3ubuntu0.1~esm1, 3.2.1-3ubuntu0.1~esm2, 4.0.20-2, 4.0.20-2ubuntu1, 4.0.20-2ubuntu1.1, 4.0.20-2ubuntu1.1+esm1, 4.3.2-4, 4.3.3-1, 4.3.3-1.1build1, 4.3.3-1.1build2, 4.3.3-1.1build3, 4.3.3-1.1ubuntu0.1~esm1, 4.3.3-1.1ubuntu0.1~esm2, 4.3.5-1, 4.3.5-3, 4.3.5-3ubuntu1, 4.3.5-3ubuntu1.1
- Fixed versions
- 1.7.1-1ubuntu0.1~esm1, 2.0.3-3ubuntu0.1~esm1, 3.2.1-3ubuntu0.1~esm3, 4.0.20-2ubuntu1.1+esm2, 4.3.3-1.1ubuntu0.1~esm3, 4.3.5-3ubuntu1.2+esm1
- CVEs
- CVE-2026-19773
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 28 Oct 2026, 09:08 UTC · Revision 1
Source evidence
libwebsockets HTTP/2 HPACK Path Header Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of libwebsockets. Authentication is not required to exploit this vulnerability. The specific flaw exists within the parsing of HTTP/2 HPACK path header. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of an allocated buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-31036.
osv:UBUNTU-CVE-2026-19773
libwebsockets
Fixed versions: 1.7.1-1ubuntu0.1~esm1
libwebsockets
Fixed versions: 2.0.3-3ubuntu0.1~esm1
libwebsockets
Fixed versions: 3.2.1-3ubuntu0.1~esm3
libwebsockets
Fixed versions: 4.0.20-2ubuntu1.1+esm2
libwebsockets
Fixed versions: 4.3.3-1.1ubuntu0.1~esm3
libwebsockets
Fixed versions: 4.3.5-3ubuntu1.2+esm1
Complete source record
{
"id": "77264edd6e49c87ba20ce3cd565b546f8dbb321bad1e5c2b6fcba58bc9aeaa4a",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-19773",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-19773",
"summary": "libwebsockets HTTP/2 HPACK Path Header Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of libwebsockets. Authentication is not required to exploit this vulnerability. The specific flaw exists within the parsing of HTTP/2 HPACK path header. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of an allocated buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-31036.",
"evidence": "osv:UBUNTU-CVE-2026-19773",
"products": [
{
"name": {
"value": "libwebsockets",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "1.7.1-1ubuntu0.1~esm1",
"evidence": "/affected/0/ranges"
}
],
"affected_versions": [
{
"value": "1.2.2-1",
"evidence": "/affected/0/versions"
},
{
"value": "1.6.0-3",
"evidence": "/affected/0/versions"
},
{
"value": "1.6.0-4",
"evidence": "/affected/0/versions"
},
{
"value": "1.6.0-5",
"evidence": "/affected/0/versions"
},
{
"value": "1.6.1-1",
"evidence": "/affected/0/versions"
},
{
"value": "1.7.0-1ubuntu1",
"evidence": "/affected/0/versions"
},
{
"value": "1.7.0-2",
"evidence": "/affected/0/versions"
},
{
"value": "1.7.1-1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "libwebsockets",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "2.0.3-3ubuntu0.1~esm1",
"evidence": "/affected/1/ranges"
}
],
"affected_versions": [
{
"value": "2.0.3-3",
"evidence": "/affected/1/versions"
},
{
"value": "2.0.3-3build1",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "libwebsockets",
"evidence": "/affected/2/package/name"
},
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{
"value": "3.2.1-3ubuntu0.1~esm3",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": [
{
"value": "2.0.3-3build1",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.1-3",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.1-3ubuntu0.1~esm1",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.1-3ubuntu0.1~esm2",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "libwebsockets",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.0.20-2ubuntu1.1+esm2",
"evidence": "/affected/3/ranges"
}
],
"affected_versions": [
{
"value": "4.0.20-2",
"evidence": "/affected/3/versions"
},
{
"value": "4.0.20-2ubuntu1",
"evidence": "/affected/3/versions"
},
{
"value": "4.0.20-2ubuntu1.1",
"evidence": "/affected/3/versions"
},
{
"value": "4.0.20-2ubuntu1.1+esm1",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "libwebsockets",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.3.3-1.1ubuntu0.1~esm3",
"evidence": "/affected/4/ranges"
}
],
"affected_versions": [
{
"value": "4.3.2-4",
"evidence": "/affected/4/versions"
},
{
"value": "4.3.3-1",
"evidence": "/affected/4/versions"
},
{
"value": "4.3.3-1.1build1",
"evidence": "/affected/4/versions"
},
{
"value": "4.3.3-1.1build2",
"evidence": "/affected/4/versions"
},
{
"value": "4.3.3-1.1build3",
"evidence": "/affected/4/versions"
},
{
"value": "4.3.3-1.1ubuntu0.1~esm1",
"evidence": "/affected/4/versions"
},
{
"value": "4.3.3-1.1ubuntu0.1~esm2",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "libwebsockets",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.3.5-3ubuntu1.2+esm1",
"evidence": "/affected/5/ranges"
}
],
"affected_versions": [
{
"value": "4.3.5-1",
"evidence": "/affected/5/versions"
},
{
"value": "4.3.5-3",
"evidence": "/affected/5/versions"
},
{
"value": "4.3.5-3ubuntu1",
"evidence": "/affected/5/versions"
},
{
"value": "4.3.5-3ubuntu1.1",
"evidence": "/affected/5/versions"
}
]
}
],
"severity": "critical",
"structured": {
"id": "UBUNTU-CVE-2026-19773",
"aliases": [
"UBUNTU-CVE-2026-19773"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.7.1-1ubuntu0.1~esm1"
}
]
}
],
"package": {
"name": "libwebsockets",
"purl": "pkg:deb/ubuntu/libwebsockets?arch=source&distro=esm-apps-legacy%2Fxenial",
"ecosystem": "Ubuntu:Pro:16.04:LTS"
},
"versions": [
"1.2.2-1",
"1.6.0-3",
"1.6.0-4",
"1.6.0-5",
"1.6.1-1",
"1.7.0-1ubuntu1",
"1.7.0-2",
"1.7.1-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19773.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libwebsockets-test-server",
"binary_version": "1.7.1-1ubuntu0.1~esm1"
},
{
"binary_name": "libwebsockets-test-server-common",
"binary_version": "1.7.1-1ubuntu0.1~esm1"
},
{
"binary_name": "libwebsockets7",
"binary_version": "1.7.1-1ubuntu0.1~esm1"
}
],
"availability": "Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "2.0.3-3ubuntu0.1~esm1"
}
]
}
],
"package": {
"name": "libwebsockets",
"purl": "pkg:deb/ubuntu/libwebsockets?arch=source&distro=esm-apps%2Fbionic",
"ecosystem": "Ubuntu:Pro:18.04:LTS"
},
"versions": [
"2.0.3-3",
"2.0.3-3build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19773.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libwebsockets-test-server",
"binary_version": "2.0.3-3ubuntu0.1~esm1"
},
{
"binary_name": "libwebsockets-test-server-common",
"binary_version": "2.0.3-3ubuntu0.1~esm1"
},
{
"binary_name": "libwebsockets8",
"binary_version": "2.0.3-3ubuntu0.1~esm1"
}
],
"availability": "Available with Ubuntu Pro: https://ubuntu.com/pro"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "3.2.1-3ubuntu0.1~esm3"
}
]
}
],
"package": {
"name": "libwebsockets",
"purl": "pkg:deb/ubuntu/libwebsockets?arch=source&distro=esm-apps%2Ffocal",
"ecosystem": "Ubuntu:Pro:20.04:LTS"
},
"versions": [
"2.0.3-3build1",
"3.2.1-3",
"3.2.1-3ubuntu0.1~esm1",
"3.2.1-3ubuntu0.1~esm2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19773.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libwebsockets-test-server",
"binary_version": "3.2.1-3ubuntu0.1~esm3"
},
{
"binary_name": "libwebsockets-test-server-common",
"binary_version": "3.2.1-3ubuntu0.1~esm3"
},
{
"binary_name": "libwebsockets15",
"binary_version": "3.2.1-3ubuntu0.1~esm3"
}
],
"availability": "Available with Ubuntu Pro: https://ubuntu.com/pro"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
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{
"fixed": "4.0.20-2ubuntu1.1+esm2"
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]
}
],
"package": {
"name": "libwebsockets",
"purl": "pkg:deb/ubuntu/libwebsockets?arch=source&distro=esm-apps%2Fjammy",
"ecosystem": "Ubuntu:Pro:22.04:LTS"
},
"versions": [
"4.0.20-2",
"4.0.20-2ubuntu1",
"4.0.20-2ubuntu1.1",
"4.0.20-2ubuntu1.1+esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19773.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libwebsockets-test-server",
"binary_version": "4.0.20-2ubuntu1.1+esm2"
},
{
"binary_name": "libwebsockets-test-server-common",
"binary_version": "4.0.20-2ubuntu1.1+esm2"
},
{
"binary_name": "libwebsockets16",
"binary_version": "4.0.20-2ubuntu1.1+esm2"
}
],
"availability": "Available with Ubuntu Pro: https://ubuntu.com/pro"
}
},
{
"ranges": [
{
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{
"introduced": "0"
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{
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]
}
],
"package": {
"name": "libwebsockets",
"purl": "pkg:deb/ubuntu/libwebsockets?arch=source&distro=esm-apps%2Fnoble",
"ecosystem": "Ubuntu:Pro:24.04:LTS"
},
"versions": [
"4.3.2-4",
"4.3.3-1",
"4.3.3-1.1build1",
"4.3.3-1.1build2",
"4.3.3-1.1build3",
"4.3.3-1.1ubuntu0.1~esm1",
"4.3.3-1.1ubuntu0.1~esm2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19773.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libwebsockets-evlib-ev",
"binary_version": "4.3.3-1.1ubuntu0.1~esm3"
},
{
"binary_name": "libwebsockets-evlib-glib",
"binary_version": "4.3.3-1.1ubuntu0.1~esm3"
},
{
"binary_name": "libwebsockets-evlib-uv",
"binary_version": "4.3.3-1.1ubuntu0.1~esm3"
},
{
"binary_name": "libwebsockets-test-server",
"binary_version": "4.3.3-1.1ubuntu0.1~esm3"
},
{
"binary_name": "libwebsockets-test-server-common",
"binary_version": "4.3.3-1.1ubuntu0.1~esm3"
},
{
"binary_name": "libwebsockets19t64",
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}
],
"availability": "Available with Ubuntu Pro: https://ubuntu.com/pro"
}
},
{
"ranges": [
{
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{
"introduced": "0"
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{
"fixed": "4.3.5-3ubuntu1.2+esm1"
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]
}
],
"package": {
"name": "libwebsockets",
"purl": "pkg:deb/ubuntu/libwebsockets?arch=source&distro=esm-apps%2Fresolute",
"ecosystem": "Ubuntu:Pro:26.04:LTS"
},
"versions": [
"4.3.5-1",
"4.3.5-3",
"4.3.5-3ubuntu1",
"4.3.5-3ubuntu1.1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19773.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libwebsockets-evlib-ev",
"binary_version": "4.3.5-3ubuntu1.2+esm1"
},
{
"binary_name": "libwebsockets-evlib-glib",
"binary_version": "4.3.5-3ubuntu1.2+esm1"
},
{
"binary_name": "libwebsockets-evlib-uv",
"binary_version": "4.3.5-3ubuntu1.2+esm1"
},
{
"binary_name": "libwebsockets-test-server",
"binary_version": "4.3.5-3ubuntu1.2+esm1"
},
{
"binary_name": "libwebsockets-test-server-common",
"binary_version": "4.3.5-3ubuntu1.2+esm1"
},
{
"binary_name": "libwebsockets19t64",
"binary_version": "4.3.5-3ubuntu1.2+esm1"
}
],
"availability": "Available with Ubuntu Pro: https://ubuntu.com/pro"
}
}
],
"modified": "2026-10-08T12:53:39.042783661Z",
"provider": "osv",
"upstream": [
"CVE-2026-19773"
],
"references": [
"https://ubuntu.com/security/CVE-2026-19773",
"https://www.cve.org/CVERecord?id=CVE-2026-19773",
"https://ubuntu.com/security/notices/USN-8893-1"
]
},
"related_cves": [
{
"value": "CVE-2026-19773",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 99575,
"published_at": "2026-09-15T19:17:00+00:00"
}