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

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

16 Apr 2026, 16:54

Type	Values Removed	Values Added
References	~~() https://github.com/rack/rack/security/advisories/GHSA-8vqr-qjwx-82mw -~~	() https://github.com/rack/rack/security/advisories/GHSA-8vqr-qjwx-82mw - Vendor Advisory
CPE		cpe:2.3:a:rack:rack::::::ruby::*
First Time		Rack rack Rack

02 Apr 2026, 17:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-04-02 17:16

Updated : 2026-04-16 16:54

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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