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` can accumulate unbounded data when a multipart part’s header block never terminates with the required blank line (`CRLFCRLF`). The parser keeps appending incoming bytes to memory without a size cap, allowing a remote attacker to exhaust memory and cause a denial of service (DoS). Attackers can send incomplete multipart headers to trigger high memory use, leading to process termination (OOM) or severe slowdown. The effect scales with request size limits and concurrency. All applications handling multipart uploads may be affected. Versions 2.2.19, 3.1.17, and 3.2.2 cap per-part header size (e.g., 64 KiB). As a workaround, restrict maximum request sizes at the proxy or web server layer (e.g., Nginx `client_max_body_size`).
- 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-2025-61772
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 23:06 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` can accumulate unbounded data when a multipart part’s header block never terminates with the required blank line (`CRLFCRLF`). The parser keeps appending incoming bytes to memory without a size cap, allowing a remote attacker to exhaust memory and cause a denial of service (DoS). Attackers can send incomplete multipart headers to trigger high memory use, leading to process termination (OOM) or severe slowdown. The effect scales with request size limits and concurrency. All applications handling multipart uploads may be affected. Versions 2.2.19, 3.1.17, and 3.2.2 cap per-part header size (e.g., 64 KiB). As a workaround, restrict maximum request sizes at the proxy or web server layer (e.g., Nginx `client_max_body_size`).
osv:DEBIAN-CVE-2025-61772
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": "53175aa7f3b2d4426c38c6e547deef94f4b27d3a60bdfbad3f5cd0c3b94384d7",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2025-61772",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2025-61772",
"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` can accumulate unbounded data when a multipart part’s header block never terminates with the required blank line (`CRLFCRLF`). The parser keeps appending incoming bytes to memory without a size cap, allowing a remote attacker to exhaust memory and cause a denial of service (DoS). Attackers can send incomplete multipart headers to trigger high memory use, leading to process termination (OOM) or severe slowdown. The effect scales with request size limits and concurrency. All applications handling multipart uploads may be affected. Versions 2.2.19, 3.1.17, and 3.2.2 cap per-part header size (e.g., 64 KiB). As a workaround, restrict maximum request sizes at the proxy or web server layer (e.g., Nginx `client_max_body_size`).",
"evidence": "osv:DEBIAN-CVE-2025-61772",
"products": [
{
"name": {
"value": "ruby-rack",
"evidence": "/affected/0/package/name"
},
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{
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"severity": "high",
"structured": {
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"aliases": [
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"metrics": [
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}
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"affected": [
{
"ranges": [
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"type": "ECOSYSTEM",
"events": [
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{
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"package": {
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"ecosystem": "Debian:12"
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"versions": [
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"ecosystem_specific": {
"urgency": "not yet assigned"
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},
{
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],
"package": {
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"purl": "pkg:deb/debian/ruby-rack?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"versions": [
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],
"database_specific": {
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"ecosystem_specific": {
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{
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"package": {
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"versions": [
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},
"ecosystem_specific": {
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}
}
],
"modified": "2026-10-23T17:47:34.801594138Z",
"provider": "osv",
"upstream": [
"CVE-2025-61772"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2025-61772"
]
},
"related_cves": [
{
"value": "CVE-2025-61772",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 417735,
"published_at": "2025-10-07T15:16:03.28+00:00"
}