Description
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.
Published: 2025-10-07
Score: 7.5 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

No analysis available yet.

Remediation

No remediation available yet.

Tracking

Sign in to view the affected projects.

Advisories
Source ID Title
Debian DLA Debian DLA DLA-4357-1 ruby-rack security update
Debian DSA Debian DSA DSA-6048-1 ruby-rack security update
Github GHSA Github GHSA GHSA-w9pc-fmgc-vxvw Rack: Multipart parser buffers large non‑file fields entirely in memory, enabling DoS (memory exhaustion)
History

Tue, 14 Oct 2025 12:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Important


Fri, 10 Oct 2025 17:00:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*

Wed, 08 Oct 2025 13:45:00 +0000

Type Values Removed Values Added
First Time appeared Rack
Rack rack
Vendors & Products Rack
Rack rack

Tue, 07 Oct 2025 18:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 07 Oct 2025 15:00:00 +0000

Type Values Removed Values Added
Description 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.
Title Rack's multipart parser buffers large non‑file fields entirely in memory, enabling DoS (memory exhaustion)
Weaknesses CWE-400
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2025-10-07T17:52:09.399Z

Reserved: 2025-09-30T19:43:49.900Z

Link: CVE-2025-61771

cve-icon Vulnrichment

Updated: 2025-10-07T17:52:01.550Z

cve-icon NVD

Status : Analyzed

Published: 2025-10-07T15:16:03.123

Modified: 2025-10-10T16:45:09.960

Link: CVE-2025-61771

cve-icon Redhat

Severity : Important

Publid Date: 2025-10-07T14:42:53Z

Links: CVE-2025-61771 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2025-10-08T13:36:33Z

Weaknesses