CVE-2026-34829

Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Multipart::Parser only wraps the request body in a BoundedIO when CONTENT_LENGTH is present. When a multipart/form-data request is sent without a Content-Length header, such as with HTTP chunked transfer encoding, multipart parsing continues until end-of-stream with no total size limit. For file parts, the uploaded body is written directly to a temporary file on disk rather than being constrained by the buffered in-memory upload limit. An unauthenticated attacker can therefore stream an arbitrarily large multipart file upload and consume unbounded disk space. This results in a denial of service condition for Rack applications that accept multipart form data. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.

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/security/advisories/GHSA-8vqr-qjwx-82mw	Vendor Advisory
https://access.redhat.com/security/cve/CVE-2026-34829
https://bugzilla.redhat.com/show_bug.cgi?id=2454488
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34829.json

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 : 2026-04-02 17:16

Updated : 2026-07-24 21:10

NVD link : CVE-2026-34829

Mitre link : CVE-2026-34829

CVE.ORG link : CVE-2026-34829

JSON object : View

Products Affected

rack

rack

CWE

CWE-400

Uncontrolled Resource Consumption

CWE-770

Allocation of Resources Without Limits or Throttling

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Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Multipart::Parser only wraps the request body in a BoundedIO when CONTENT_LENGTH is present. When a multipart/form-data request is sent without a Content-Length header, such as with HTTP chunked transfer encoding, multipart parsing continues until end-of-stream with no total size limit. For file parts, the uploaded body is written directly to a temporary file on disk rather than being constrained by the buffered in-memory upload limit. An unauthenticated attacker can therefore stream an arbitrarily large multipart file upload and consume unbounded disk space. This results in a denial of service condition for Rack applications that accept multipart form data. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6."}, {"lang": "es", "value": "Rack es una interfaz modular de servidor web Ruby. Antes de las versiones 2.2.23, 3.1.21 y 3.2.6, Rack::Multipart::Parser solo envuelve el cuerpo de la solicitud en un BoundedIO cuando CONTENT_LENGTH est\u00e1 presente. Cuando se env\u00eda una solicitud multipart/form-data sin una cabecera Content-Length, como con la codificaci\u00f3n de transferencia fragmentada HTTP, el an\u00e1lisis multipart contin\u00faa hasta el final del flujo sin un l\u00edmite de tama\u00f1o total. Para las partes de archivos, el cuerpo subido se escribe directamente en un archivo temporal en disco en lugar de estar limitado por el l\u00edmite de carga en memoria almacenado en b\u00fafer. Un atacante no autenticado puede, por lo tanto, transmitir una carga de archivo multipart arbitrariamente grande y consumir espacio en disco ilimitado. Esto resulta en una condici\u00f3n de denegaci\u00f3n de servicio para las aplicaciones Rack que aceptan datos de formulario multipart. Este problema ha sido parcheado en las versiones 2.2.23, 3.1.21 y 3.2.6."}], "lastModified": "2026-07-24T21:10:00.143", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*", "vulnerable": true, "matchCriteriaId": "AD5DE7DE-3A8B-4064-A7D5-1E117A101E81", "versionEndExcluding": "2.2.23"}, {"criteria": "cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*", "vulnerable": true, "matchCriteriaId": "6948AAA6-873D-46BA-AA22-4C81138128E1", "versionEndExcluding": "3.1.21", "versionStartIncluding": "3.0.0"}, {"criteria": "cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*", "vulnerable": true, "matchCriteriaId": "3FB592AD-E826-49BE-AC6D-E5F55FDCC96E", "versionEndExcluding": "3.2.6", "versionStartIncluding": "3.2.0"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}