CVE-2025-61919

Description

Rack is a modular Ruby web server interface. Prior to versions 2.2.20, 3.1.18, and 3.2.3, `Rack::Request#POST` reads the entire request body into memory for `Content-Type: application/x-www-form-urlencoded`, calling `rack.input.read(nil)` without enforcing a length or cap. Large request bodies can therefore be buffered completely into process memory before parsing, leading to denial of service (DoS) through memory exhaustion. Users should upgrade to Rack version 2.2.20, 3.1.18, or 3.2.3, anu of which enforces form parameter limits using `query_parser.bytesize_limit`, preventing unbounded reads of `application/x-www-form-urlencoded` bodies. Additionally, enforce strict maximum body size at the proxy or web server layer (e.g., Nginx `client_max_body_size`, Apache `LimitRequestBody`).

Status

Show unmaintained releases

Package	Ubuntu Release	Status
ruby-rack	25.10 questing	Fixed 3.1.16-0.1ubuntu0.1
	25.04 plucky	Ignored end of life, was needed
	24.04 LTS noble	Fixed 2.2.7-1ubuntu0.5
	22.04 LTS jammy	Fixed 2.1.4-5ubuntu1.2
	20.04 LTS focal	Fixed 2.0.7-2ubuntu0.1+esm8
	18.04 LTS bionic	Ignored changes too intrusive
	16.04 LTS xenial	Ignored changes too intrusive
	14.04 LTS trusty	Ignored changes too intrusive

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Severity score breakdown

Parameter	Value
Base score	7.5 · High
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality	None
Integrity impact	None
Availability impact	High
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

Related Ubuntu Security Notices (USN)

USN-7960-1
Rack vulnerabilities
14 January 2026