MediumFix available
haproxy — security advisory
An issue was discovered in HAProxy before 3.3.6. The HTTP/3 parser does not check that the received body length matches a previously announced content-length when the stream is closed via a frame with an empty payload. This can cause desynchronization issues with the backend server and could be used for request smuggling. The earliest affected version is 2.6.
- Products
- haproxy
- Affected versions
- 2.6.12-1, 2.6.12-1+deb12u1, 2.6.12-1+deb12u2, 2.6.12-1+deb12u3, 3.0.11-1, 3.0.11-1+deb13u1, 3.0.11-1+deb13u2, 3.1.0-1, 3.1.0-2, 3.1.1-1, 3.1.2-1, 3.1.3-1, 3.1.5-1, 3.1.6-1, 3.1.7-1, 3.2.0-1, 3.2.1-1, 3.2.10-1, 3.2.11-1, 3.2.11-2, 3.2.12-1, 3.2.13-1, 3.2.14-1, 3.2.3-1, 3.2.3-2, 3.2.4-1, 3.2.5-1, 3.2.5-2, 3.2.6-1, 3.2.7-1, 3.2.8-1, 3.2.9-1
- Fixed versions
- 2.6.12-1+deb12u4, 3.0.11-1+deb13u3, 3.2.15-1
- CVEs
- CVE-2026-33555
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 23:17 UTC · Revision 1
Source evidence
An issue was discovered in HAProxy before 3.3.6. The HTTP/3 parser does not check that the received body length matches a previously announced content-length when the stream is closed via a frame with an empty payload. This can cause desynchronization issues with the backend server and could be used for request smuggling. The earliest affected version is 2.6.
osv:DEBIAN-CVE-2026-33555
haproxy
Fixed versions: 2.6.12-1+deb12u4
haproxy
Fixed versions: 3.0.11-1+deb13u3
haproxy
Fixed versions: 3.2.15-1
Complete source record
{
"id": "4ede8e6161cccaa39dd6838c72649618e11e78a0e5d4e476bafeeb2e1e04a37d",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-33555",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2026-33555",
"summary": "An issue was discovered in HAProxy before 3.3.6. The HTTP/3 parser does not check that the received body length matches a previously announced content-length when the stream is closed via a frame with an empty payload. This can cause desynchronization issues with the backend server and could be used for request smuggling. The earliest affected version is 2.6.",
"evidence": "osv:DEBIAN-CVE-2026-33555",
"products": [
{
"name": {
"value": "haproxy",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "2.6.12-1+deb12u4",
"evidence": "/affected/0/ranges"
}
],
"affected_versions": [
{
"value": "2.6.12-1",
"evidence": "/affected/0/versions"
},
{
"value": "2.6.12-1+deb12u1",
"evidence": "/affected/0/versions"
},
{
"value": "2.6.12-1+deb12u2",
"evidence": "/affected/0/versions"
},
{
"value": "2.6.12-1+deb12u3",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "haproxy",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "3.0.11-1+deb13u3",
"evidence": "/affected/1/ranges"
}
],
"affected_versions": [
{
"value": "3.0.11-1",
"evidence": "/affected/1/versions"
},
{
"value": "3.0.11-1+deb13u1",
"evidence": "/affected/1/versions"
},
{
"value": "3.0.11-1+deb13u2",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "haproxy",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "3.2.15-1",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": [
{
"value": "3.0.11-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.1.0-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.1.0-2",
"evidence": "/affected/2/versions"
},
{
"value": "3.1.1-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.1.2-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.1.3-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.1.5-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.1.6-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.1.7-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.0-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.1-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.10-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.11-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.11-2",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.12-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.13-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.14-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.3-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.3-2",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.4-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.5-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.5-2",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.6-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.7-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.8-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.9-1",
"evidence": "/affected/2/versions"
}
]
}
],
"severity": "medium",
"structured": {
"id": "DEBIAN-CVE-2026-33555",
"aliases": [
"DEBIAN-CVE-2026-33555"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "2.6.12-1+deb12u4"
}
]
}
],
"package": {
"name": "haproxy",
"purl": "pkg:deb/debian/haproxy?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
"2.6.12-1",
"2.6.12-1+deb12u1",
"2.6.12-1+deb12u2",
"2.6.12-1+deb12u3"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33555.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "3.0.11-1+deb13u3"
}
]
}
],
"package": {
"name": "haproxy",
"purl": "pkg:deb/debian/haproxy?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"versions": [
"3.0.11-1",
"3.0.11-1+deb13u1",
"3.0.11-1+deb13u2"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33555.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "3.2.15-1"
}
]
}
],
"package": {
"name": "haproxy",
"purl": "pkg:deb/debian/haproxy?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"3.0.11-1",
"3.1.0-1",
"3.1.0-2",
"3.1.1-1",
"3.1.2-1",
"3.1.3-1",
"3.1.5-1",
"3.1.6-1",
"3.1.7-1",
"3.2.0-1",
"3.2.1-1",
"3.2.10-1",
"3.2.11-1",
"3.2.11-2",
"3.2.12-1",
"3.2.13-1",
"3.2.14-1",
"3.2.3-1",
"3.2.3-2",
"3.2.4-1",
"3.2.5-1",
"3.2.5-2",
"3.2.6-1",
"3.2.7-1",
"3.2.8-1",
"3.2.9-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33555.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-23T17:47:39.759565051Z",
"provider": "osv",
"upstream": [
"CVE-2026-33555"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2026-33555"
]
},
"related_cves": [
{
"value": "CVE-2026-33555",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 418202,
"published_at": "2026-04-13T17:16:28.237+00:00"
}