High
puma — security advisory
Puma is a Ruby/Rack web server built for parallelism. From 5.5.0 until 7.2.1 and 8.0.2, when PROXY protocol v1 support is enabled, Puma reads incoming bytes into an internal buffer while waiting for CRLF to determine whether a PROXY v1 line is present, allowing an attacker that continuously sends bytes without CRLF to cause unbounded in-process memory growth and additional CPU cost from repeatedly scanning the growing buffer. This issue is fixed in versions 7.2.1 and 8.0.2.
- Products
- puma
- Affected versions
- 3.12.0-2ubuntu1, 3.12.0-4ubuntu1, 3.12.4-1ubuntu2, 3.12.4-1ubuntu2+esm1, 3.12.4-1ubuntu2+esm2, 4.3.6-1ubuntu4, 5.5.2-2ubuntu2, 5.5.2-2ubuntu2+esm1, 5.5.2-2ubuntu2+esm2, 5.6.5-4ubuntu2, 5.6.5-4ubuntu3, 6.4.2-4ubuntu1, 6.4.2-4ubuntu3, 6.4.2-4ubuntu4, 6.4.2-4ubuntu4.3, 6.6.0-4, 6.6.0-4build1, 8.0.2-3build1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-47736
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 03:06 UTC · Revision 1
Source evidence
Puma is a Ruby/Rack web server built for parallelism. From 5.5.0 until 7.2.1 and 8.0.2, when PROXY protocol v1 support is enabled, Puma reads incoming bytes into an internal buffer while waiting for CRLF to determine whether a PROXY v1 line is present, allowing an attacker that continuously sends bytes without CRLF to cause unbounded in-process memory growth and additional CPU cost from repeatedly scanning the growing buffer. This issue is fixed in versions 7.2.1 and 8.0.2.
osv:UBUNTU-CVE-2026-47736
puma
Fixed versions: Not specified
puma
Fixed versions: Not specified
puma
Fixed versions: Not specified
puma
Fixed versions: Not specified
puma
Fixed versions: Not specified
Complete source record
{
"id": "1d0ae8b002608621512b1dd35d955f876ef6ee1da838229470618448860d78ee",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-47736",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-47736",
"summary": "Puma is a Ruby/Rack web server built for parallelism. From 5.5.0 until 7.2.1 and 8.0.2, when PROXY protocol v1 support is enabled, Puma reads incoming bytes into an internal buffer while waiting for CRLF to determine whether a PROXY v1 line is present, allowing an attacker that continuously sends bytes without CRLF to cause unbounded in-process memory growth and additional CPU cost from repeatedly scanning the growing buffer. This issue is fixed in versions 7.2.1 and 8.0.2.",
"evidence": "osv:UBUNTU-CVE-2026-47736",
"products": [
{
"name": {
"value": "puma",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.12.0-2ubuntu1",
"evidence": "/affected/0/versions"
},
{
"value": "3.12.0-4ubuntu1",
"evidence": "/affected/0/versions"
},
{
"value": "3.12.4-1ubuntu2",
"evidence": "/affected/0/versions"
},
{
"value": "3.12.4-1ubuntu2+esm1",
"evidence": "/affected/0/versions"
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{
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"evidence": "/affected/0/versions"
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{
"name": {
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"evidence": "/affected/1/package/name"
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"affected_versions": [
{
"value": "4.3.6-1ubuntu4",
"evidence": "/affected/1/versions"
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{
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"evidence": "/affected/1/versions"
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{
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"evidence": "/affected/1/versions"
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{
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"evidence": "/affected/1/versions"
}
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{
"name": {
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"evidence": "/affected/2/package/name"
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"prerequisites": [],
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"affected_versions": [
{
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"evidence": "/affected/2/versions"
},
{
"value": "5.6.5-4ubuntu3",
"evidence": "/affected/2/versions"
},
{
"value": "6.4.2-4ubuntu1",
"evidence": "/affected/2/versions"
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{
"value": "6.4.2-4ubuntu3",
"evidence": "/affected/2/versions"
},
{
"value": "6.4.2-4ubuntu4",
"evidence": "/affected/2/versions"
},
{
"value": "6.4.2-4ubuntu4.3",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
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"evidence": "/affected/3/package/name"
},
"prerequisites": [],
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"affected_versions": [
{
"value": "6.6.0-4build1",
"evidence": "/affected/3/versions"
},
{
"value": "8.0.2-3build1",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
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"evidence": "/affected/4/package/name"
},
"prerequisites": [],
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"affected_versions": [
{
"value": "6.6.0-4",
"evidence": "/affected/4/versions"
},
{
"value": "6.6.0-4build1",
"evidence": "/affected/4/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "UBUNTU-CVE-2026-47736",
"aliases": [
"UBUNTU-CVE-2026-47736"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
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"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
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"purl": "pkg:deb/ubuntu/puma?arch=source&distro=esm-apps%2Ffocal",
"ecosystem": "Ubuntu:Pro:20.04:LTS"
},
"versions": [
"3.12.0-2ubuntu1",
"3.12.0-4ubuntu1",
"3.12.4-1ubuntu2",
"3.12.4-1ubuntu2+esm1",
"3.12.4-1ubuntu2+esm2"
],
"database_specific": {
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"package": {
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"ecosystem": "Ubuntu:Pro:22.04:LTS"
},
"versions": [
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"5.5.2-2ubuntu2",
"5.5.2-2ubuntu2+esm1",
"5.5.2-2ubuntu2+esm2"
],
"database_specific": {
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},
"ecosystem_specific": {
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]
}
},
{
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"ecosystem": "Ubuntu:24.04:LTS"
},
"versions": [
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"5.6.5-4ubuntu3",
"6.4.2-4ubuntu1",
"6.4.2-4ubuntu3",
"6.4.2-4ubuntu4",
"6.4.2-4ubuntu4.3"
],
"database_specific": {
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},
"ecosystem_specific": {
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"package": {
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"ecosystem": "Ubuntu:26.10"
},
"versions": [
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"8.0.2-3build1"
],
"database_specific": {
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},
"ecosystem_specific": {
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{
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"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
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],
"database_specific": {
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},
"ecosystem_specific": {
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{
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]
}
}
],
"modified": "2026-10-17T13:00:20.419980931Z",
"provider": "osv",
"upstream": [
"CVE-2026-47736"
],
"references": [
"https://ubuntu.com/security/CVE-2026-47736",
"https://www.cve.org/CVERecord?id=CVE-2026-47736",
"https://github.com/puma/puma/commit/439c6136d9c2275721b7864db3ee78af7c80889f",
"https://github.com/puma/puma/commit/ebe9db3929ab8299d19c8f5b41e8ef4f4b22fa58",
"https://github.com/puma/puma/releases/tag/v7.2.1",
"https://github.com/puma/puma/releases/tag/v8.0.2",
"https://github.com/puma/puma/security/advisories/GHSA-qpgp-93vx-g8v8"
]
},
"related_cves": [
{
"value": "CVE-2026-47736",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 360429,
"published_at": "2026-07-14T20:17:00+00:00"
}