CVE-2025-61771

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.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/rack/rack/commit/589127f4ac8b5cf11cf88fb0cd116ffed4d2181e	Patch
https://github.com/rack/rack/commit/d869fed663b113b95a74ad53e1b5cae6ab31f29e	Patch
https://github.com/rack/rack/commit/e08f78c656c9394d6737c022bde087e0f33336fd	Patch
https://github.com/rack/rack/security/advisories/GHSA-w9pc-fmgc-vxvw	Vendor Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:rack:rack::::::ruby::*
	cpe:2.3:a:rack:rack::::::ruby::*
	cpe:2.3:a:rack:rack::::::ruby::*

History

No history.

Information

Published : 2025-10-07 15:16

Updated : 2025-10-10 16:45

NVD link : CVE-2025-61771

Mitre link : CVE-2025-61771

CVE.ORG link : CVE-2025-61771

JSON object : View

Products Affected

rack

rack

CWE

CWE-400

Uncontrolled Resource Consumption

{"id": "CVE-2025-61771", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Secondary", "source": "[email protected]", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 3.9}]}, "published": "2025-10-07T15:16:03.123", "references": [{"url": "https://github.com/rack/rack/commit/589127f4ac8b5cf11cf88fb0cd116ffed4d2181e", "tags": ["Patch"], "source": "[email protected]"}, {"url": "https://github.com/rack/rack/commit/d869fed663b113b95a74ad53e1b5cae6ab31f29e", "tags": ["Patch"], "source": "[email protected]"}, {"url": "https://github.com/rack/rack/commit/e08f78c656c9394d6737c022bde087e0f33336fd", "tags": ["Patch"], "source": "[email protected]"}, {"url": "https://github.com/rack/rack/security/advisories/GHSA-w9pc-fmgc-vxvw", "tags": ["Vendor Advisory"], "source": "[email protected]"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "[email protected]", "description": [{"lang": "en", "value": "CWE-400"}]}], "descriptions": [{"lang": "en", "value": "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."}], "lastModified": "2025-10-10T16:45:09.960", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*", "vulnerable": true, "matchCriteriaId": "EBB6060B-A06F-4A88-8457-AD850E63E562", "versionEndExcluding": "2.2.19"}, {"criteria": "cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*", "vulnerable": true, "matchCriteriaId": "850EC79C-0F31-441F-9001-B7CA0CD7758F", "versionEndExcluding": "3.1.17", "versionStartIncluding": "3.1.0"}, {"criteria": "cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*", "vulnerable": true, "matchCriteriaId": "9A009CC5-8010-446E-A12B-BF5314CA5BEB", "versionEndExcluding": "3.2.2", "versionStartIncluding": "3.2.0"}], "operator": "OR"}]}], "sourceIdentifier": "[email protected]"}