ruby-rack — security advisory
Rack is a modular Ruby web server interface. In versions prior to 2.2.19, 3.1.17, and 3.2.2, ``Rack::Multipart::Parser` stores non-file form fields (parts without a `filename`) entirely in memory as Ruby `String` objects. A single large text field in a multipart/form-data request (hundreds of megabytes or more) can consume equivalent process memory, potentially leading to out-of-memory (OOM) conditions and denial of service (DoS). Attackers can send large non-file fields to trigger excessive memory usage. Impact scales with request size and concurrency, potentially leading to worker crashes or severe garbage-collection overhead. All Rack applications processing multipart form submissions are affected. Versions 2.2.19, 3.1.17, and 3.2.2 enforce a reasonable size cap for non-file fields (e.g., 2 MiB). Workarounds include restricting maximum request body size at the web-server or proxy layer (e.g., Nginx `client_max_body_size`) and validating and rejecting unusually large form fields at the application level.
- Products
- ruby-rack
- Affected versions
- 2.2.13-1~deb12u1, 2.2.6.4-1, 2.2.6.4-1+deb12u1, 2.2.7-1, 2.2.7-1.1, 3.1.16-0.1, 3.1.18-1~deb13u1
- Fixed versions
- 2.2.20-0+deb12u1, 3.1.18-1, 3.1.18-1~deb13u1
- CVEs
- CVE-2025-61771
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 23:33 UTC · Revision 1
Source evidence
Rack is a modular Ruby web server interface. In versions prior to 2.2.19, 3.1.17, and 3.2.2, ``Rack::Multipart::Parser` stores non-file form fields (parts without a `filename`) entirely in memory as Ruby `String` objects. A single large text field in a multipart/form-data request (hundreds of megabytes or more) can consume equivalent process memory, potentially leading to out-of-memory (OOM) conditions and denial of service (DoS). Attackers can send large non-file fields to trigger excessive memory usage. Impact scales with request size and concurrency, potentially leading to worker crashes or severe garbage-collection overhead. All Rack applications processing multipart form submissions are affected. Versions 2.2.19, 3.1.17, and 3.2.2 enforce a reasonable size cap for non-file fields (e.g., 2 MiB). Workarounds include restricting maximum request body size at the web-server or proxy layer (e.g., Nginx `client_max_body_size`) and validating and rejecting unusually large form fields at the application level.
osv:DEBIAN-CVE-2025-61771
ruby-rack
Fixed versions: 2.2.20-0+deb12u1
ruby-rack
Fixed versions: 3.1.18-1~deb13u1
ruby-rack
Fixed versions: 3.1.18-1
Complete source record
{
"id": "350155d6579c7877eda522d5dcc9356cfc495c87efb3af89cab5c2603e1f8329",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2025-61771",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2025-61771",
"summary": "Rack is a modular Ruby web server interface. In versions prior to 2.2.19, 3.1.17, and 3.2.2, ``Rack::Multipart::Parser` stores non-file form fields (parts without a `filename`) entirely in memory as Ruby `String` objects. A single large text field in a multipart/form-data request (hundreds of megabytes or more) can consume equivalent process memory, potentially leading to out-of-memory (OOM) conditions and denial of service (DoS). Attackers can send large non-file fields to trigger excessive memory usage. Impact scales with request size and concurrency, potentially leading to worker crashes or severe garbage-collection overhead. All Rack applications processing multipart form submissions are affected. Versions 2.2.19, 3.1.17, and 3.2.2 enforce a reasonable size cap for non-file fields (e.g., 2 MiB). Workarounds include restricting maximum request body size at the web-server or proxy layer (e.g., Nginx `client_max_body_size`) and validating and rejecting unusually large form fields at the application level.",
"evidence": "osv:DEBIAN-CVE-2025-61771",
"products": [
{
"name": {
"value": "ruby-rack",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "2.2.20-0+deb12u1",
"evidence": "/affected/0/ranges"
}
],
"affected_versions": [
{
"value": "2.2.13-1~deb12u1",
"evidence": "/affected/0/versions"
},
{
"value": "2.2.6.4-1",
"evidence": "/affected/0/versions"
},
{
"value": "2.2.6.4-1+deb12u1",
"evidence": "/affected/0/versions"
},
{
"value": "2.2.7-1",
"evidence": "/affected/0/versions"
},
{
"value": "2.2.7-1.1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
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"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "3.1.18-1~deb13u1",
"evidence": "/affected/1/ranges"
}
],
"affected_versions": [
{
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"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "ruby-rack",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "3.1.18-1",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": [
{
"value": "3.1.16-0.1",
"evidence": "/affected/2/versions"
},
{
"value": "3.1.18-1~deb13u1",
"evidence": "/affected/2/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "DEBIAN-CVE-2025-61771",
"aliases": [
"DEBIAN-CVE-2025-61771"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "2.2.20-0+deb12u1"
}
]
}
],
"package": {
"name": "ruby-rack",
"purl": "pkg:deb/debian/ruby-rack?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
"2.2.13-1~deb12u1",
"2.2.6.4-1",
"2.2.6.4-1+deb12u1",
"2.2.7-1",
"2.2.7-1.1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-61771.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "3.1.18-1~deb13u1"
}
]
}
],
"package": {
"name": "ruby-rack",
"purl": "pkg:deb/debian/ruby-rack?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"versions": [
"3.1.16-0.1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-61771.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "3.1.18-1"
}
]
}
],
"package": {
"name": "ruby-rack",
"purl": "pkg:deb/debian/ruby-rack?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"3.1.16-0.1",
"3.1.18-1~deb13u1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-61771.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-23T17:47:46.789523840Z",
"provider": "osv",
"upstream": [
"CVE-2025-61771"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2025-61771"
]
},
"related_cves": [
{
"value": "CVE-2025-61771",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 418901,
"published_at": "2025-10-07T15:16:03.123+00:00"
}