MediumFix available
erlang-cowboy, rabbitmq-server — security advisory
Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting') vulnerability in ninenines cowlib allows HTTP response splitting via non-VCHAR bytes in structured-fields string values. cow_http_struct_hd:escape_string/2 in cowlib only escapes \ and ", passing all other bytes through verbatim. This creates an encoder/decoder asymmetry: the matching parser accepts only printable ASCII (0x20–0x7E, excluding " and \), but the encoder emits any byte including CR and LF. An application that builds a structured HTTP header via cow_http_struct_hd:item/1 (or a higher-level wrapper such as cow_http_hd:wt_protocol/1) from attacker-controlled input can have \r\n injected into the serialized header value. Once on the wire, the injected CRLF terminates the current header and any following bytes are interpreted as a new header, enabling HTTP response splitting. This issue affects cowlib: from 2.9.0 onward.
- Products
- erlang-cowboy, rabbitmq-server
- Affected versions
- 0.10.0+dfsg1-1, 0.6.1-1, 0.6.1-2, 0.6.1-3, 0.6.1-4, 0.8.6+dfsg-1, 0.8.6+dfsg1-1, 1.0.0+dfsg1-1, 2.0.0~pre.1+dfsg1-1, 2.0.0~pre.1+dfsg1-2, 2.0.0~pre.1+dfsg1-3, 2.0.0~pre.1+dfsg1-4, 3.10.8-1.1, 3.10.8-1.1+deb12u1, 3.10.8-2, 3.10.8-3, 3.10.8-4, 3.12.1-1, 3.12.1-1.1, 4.0.5-1, 4.0.5-10, 4.0.5-11, 4.0.5-12, 4.0.5-13, 4.0.5-14, 4.0.5-2, 4.0.5-3, 4.0.5-4, 4.0.5-5, 4.0.5-6, 4.0.5-6+deb13u1, 4.0.5-6+deb13u2, 4.0.5-8, 4.0.5-9, 4.3.0-1, 4.3.0-2, 4.3.0-3, 4.3.2-1, 4.3.2-2, 4.3.2-3, 4.3.2-4, 4.3.2-5, 4.3.6-1
- Fixed versions
- 2.16.1+dfsg-1
- CVEs
- CVE-2026-43966
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 30 Oct 2026, 16:19 UTC · Revision 1
Source evidence
Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting') vulnerability in ninenines cowlib allows HTTP response splitting via non-VCHAR bytes in structured-fields string values. cow_http_struct_hd:escape_string/2 in cowlib only escapes \ and ", passing all other bytes through verbatim. This creates an encoder/decoder asymmetry: the matching parser accepts only printable ASCII (0x20–0x7E, excluding " and \), but the encoder emits any byte including CR and LF. An application that builds a structured HTTP header via cow_http_struct_hd:item/1 (or a higher-level wrapper such as cow_http_hd:wt_protocol/1) from attacker-controlled input can have \r\n injected into the serialized header value. Once on the wire, the injected CRLF terminates the current header and any following bytes are interpreted as a new header, enabling HTTP response splitting. This issue affects cowlib: from 2.9.0 onward.
osv:DEBIAN-CVE-2026-43966
erlang-cowboy
Fixed versions: 2.16.1+dfsg-1
rabbitmq-server
Fixed versions: Not specified
rabbitmq-server
Fixed versions: Not specified
rabbitmq-server
Fixed versions: Not specified
Complete source record
{
"id": "472fa78ceccff5ced766fd688bee409a6e3b56d5d2817b56789a8cb1d34cd9b0",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-43966",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2026-43966",
"summary": "Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting') vulnerability in ninenines cowlib allows HTTP response splitting via non-VCHAR bytes in structured-fields string values. cow_http_struct_hd:escape_string/2 in cowlib only escapes \\ and \", passing all other bytes through verbatim. This creates an encoder/decoder asymmetry: the matching parser accepts only printable ASCII (0x20–0x7E, excluding \" and \\), but the encoder emits any byte including CR and LF. An application that builds a structured HTTP header via cow_http_struct_hd:item/1 (or a higher-level wrapper such as cow_http_hd:wt_protocol/1) from attacker-controlled input can have \\r\\n injected into the serialized header value. Once on the wire, the injected CRLF terminates the current header and any following bytes are interpreted as a new header, enabling HTTP response splitting. This issue affects cowlib: from 2.9.0 onward.",
"evidence": "osv:DEBIAN-CVE-2026-43966",
"products": [
{
"name": {
"value": "erlang-cowboy",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
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"evidence": "/affected/0/ranges"
}
],
"affected_versions": [
{
"value": "0.10.0+dfsg1-1",
"evidence": "/affected/0/versions"
},
{
"value": "0.6.1-1",
"evidence": "/affected/0/versions"
},
{
"value": "0.6.1-2",
"evidence": "/affected/0/versions"
},
{
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"evidence": "/affected/0/versions"
},
{
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"evidence": "/affected/0/versions"
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{
"value": "0.8.6+dfsg-1",
"evidence": "/affected/0/versions"
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{
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"evidence": "/affected/0/versions"
},
{
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"evidence": "/affected/0/versions"
},
{
"value": "2.0.0~pre.1+dfsg1-1",
"evidence": "/affected/0/versions"
},
{
"value": "2.0.0~pre.1+dfsg1-2",
"evidence": "/affected/0/versions"
},
{
"value": "2.0.0~pre.1+dfsg1-3",
"evidence": "/affected/0/versions"
},
{
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"evidence": "/affected/0/versions"
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]
},
{
"name": {
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},
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{
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{
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{
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{
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{
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{
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{
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{
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{
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{
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{
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{
"value": "4.0.5-14",
"evidence": "/affected/1/versions"
},
{
"value": "4.0.5-2",
"evidence": "/affected/1/versions"
},
{
"value": "4.0.5-3",
"evidence": "/affected/1/versions"
},
{
"value": "4.0.5-4",
"evidence": "/affected/1/versions"
},
{
"value": "4.0.5-5",
"evidence": "/affected/1/versions"
},
{
"value": "4.0.5-6",
"evidence": "/affected/1/versions"
},
{
"value": "4.0.5-8",
"evidence": "/affected/1/versions"
},
{
"value": "4.0.5-9",
"evidence": "/affected/1/versions"
},
{
"value": "4.3.0-1",
"evidence": "/affected/1/versions"
},
{
"value": "4.3.0-2",
"evidence": "/affected/1/versions"
},
{
"value": "4.3.0-3",
"evidence": "/affected/1/versions"
},
{
"value": "4.3.2-1",
"evidence": "/affected/1/versions"
},
{
"value": "4.3.2-2",
"evidence": "/affected/1/versions"
},
{
"value": "4.3.2-3",
"evidence": "/affected/1/versions"
},
{
"value": "4.3.2-4",
"evidence": "/affected/1/versions"
},
{
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"evidence": "/affected/1/versions"
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{
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]
},
{
"name": {
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"evidence": "/affected/2/package/name"
},
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"affected_versions": [
{
"value": "4.0.5-10",
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},
{
"value": "4.0.5-11",
"evidence": "/affected/2/versions"
},
{
"value": "4.0.5-12",
"evidence": "/affected/2/versions"
},
{
"value": "4.0.5-13",
"evidence": "/affected/2/versions"
},
{
"value": "4.0.5-14",
"evidence": "/affected/2/versions"
},
{
"value": "4.0.5-6",
"evidence": "/affected/2/versions"
},
{
"value": "4.0.5-6+deb13u1",
"evidence": "/affected/2/versions"
},
{
"value": "4.0.5-6+deb13u2",
"evidence": "/affected/2/versions"
},
{
"value": "4.0.5-8",
"evidence": "/affected/2/versions"
},
{
"value": "4.0.5-9",
"evidence": "/affected/2/versions"
},
{
"value": "4.3.0-1",
"evidence": "/affected/2/versions"
},
{
"value": "4.3.0-2",
"evidence": "/affected/2/versions"
},
{
"value": "4.3.0-3",
"evidence": "/affected/2/versions"
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{
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"evidence": "/affected/2/versions"
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{
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"evidence": "/affected/2/versions"
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{
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"evidence": "/affected/2/versions"
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{
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"evidence": "/affected/2/versions"
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{
"value": "4.3.2-5",
"evidence": "/affected/2/versions"
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{
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}
]
},
{
"name": {
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"evidence": "/affected/3/package/name"
},
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"affected_versions": [
{
"value": "4.0.5-10",
"evidence": "/affected/3/versions"
},
{
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"evidence": "/affected/3/versions"
},
{
"value": "4.0.5-12",
"evidence": "/affected/3/versions"
},
{
"value": "4.0.5-13",
"evidence": "/affected/3/versions"
},
{
"value": "4.0.5-14",
"evidence": "/affected/3/versions"
},
{
"value": "4.0.5-6",
"evidence": "/affected/3/versions"
},
{
"value": "4.0.5-8",
"evidence": "/affected/3/versions"
},
{
"value": "4.0.5-9",
"evidence": "/affected/3/versions"
},
{
"value": "4.3.0-1",
"evidence": "/affected/3/versions"
},
{
"value": "4.3.0-2",
"evidence": "/affected/3/versions"
},
{
"value": "4.3.0-3",
"evidence": "/affected/3/versions"
},
{
"value": "4.3.2-1",
"evidence": "/affected/3/versions"
},
{
"value": "4.3.2-2",
"evidence": "/affected/3/versions"
},
{
"value": "4.3.2-3",
"evidence": "/affected/3/versions"
},
{
"value": "4.3.2-4",
"evidence": "/affected/3/versions"
},
{
"value": "4.3.2-5",
"evidence": "/affected/3/versions"
},
{
"value": "4.3.6-1",
"evidence": "/affected/3/versions"
}
]
}
],
"severity": "medium",
"structured": {
"id": "DEBIAN-CVE-2026-43966",
"aliases": [
"DEBIAN-CVE-2026-43966"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "2.16.1+dfsg-1"
}
]
}
],
"package": {
"name": "erlang-cowboy",
"purl": "pkg:deb/debian/erlang-cowboy?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
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"2.0.0~pre.1+dfsg1-1",
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"2.0.0~pre.1+dfsg1-3",
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],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-43966.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
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}
]
}
],
"package": {
"name": "rabbitmq-server",
"purl": "pkg:deb/debian/rabbitmq-server?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
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"4.0.5-6",
"4.0.5-8",
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"database_specific": {
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},
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},
{
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],
"package": {
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"ecosystem": "Debian:13"
},
"versions": [
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"4.0.5-11",
"4.0.5-12",
"4.0.5-13",
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],
"database_specific": {
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},
"ecosystem_specific": {
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}
},
{
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{
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{
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}
]
}
],
"package": {
"name": "rabbitmq-server",
"purl": "pkg:deb/debian/rabbitmq-server?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"4.0.5-10",
"4.0.5-11",
"4.0.5-12",
"4.0.5-13",
"4.0.5-14",
"4.0.5-6",
"4.0.5-8",
"4.0.5-9",
"4.3.0-1",
"4.3.0-2",
"4.3.0-3",
"4.3.2-1",
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"4.3.2-5",
"4.3.6-1"
],
"database_specific": {
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},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-15T09:47:29.061469347Z",
"provider": "osv",
"upstream": [
"CVE-2026-43966"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2026-43966"
]
},
"related_cves": [
{
"value": "CVE-2026-43966",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 327461,
"published_at": "2026-06-08T17:16:43.447+00:00"
}