Rack up to 2.2.19/3.1.17/3.2.2 Request Body Rack::Request Content-Type resource consumption

Summaryinfo

A vulnerability marked as problematic has been reported in Rack up to 2.2.19/3.1.17/3.2.2. This issue affects the function Rack::Request of the component Request Body Handler. The manipulation of the argument Content-Type leads to resource consumption. This vulnerability is uniquely identified as CVE-2025-61919. The attack is possible to be carried out remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Rack up to 2.2.19/3.1.17/3.2.2 and classified as problematic. This issue affects the function Rack::Request of the component Request Body Handler. The manipulation of the argument Content-Type with an unknown input leads to a resource consumption vulnerability. Using CWE to declare the problem leads to CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. Impacted is availability. The summary by CVE is:

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`).

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2025-61919 since 10/04/2025. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

The vulnerability scanner Nessus provides a plugin with the ID 270698 (Ruby RACK < 2.2.20 / 3.x < 3.1.18 / 3.2 < 3.2.3 Multiple Vulnerabilities), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2.2.20, 3.1.18 or 3.2.3 eliminates this vulnerability. Applying the patch 4e2c903991a790ee211a3021808ff4fd6fe82881 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (270698) and CERT Bund (WID-SEC-2025-2482). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

• Debian Linux
• Red Hat Enterprise Linux
• Oracle Linux
• RESF Rocky Linux

Productinfo

Name

• Rack

Version

• 2.2.0
• 2.2.1
• 2.2.2
• 2.2.3
• 2.2.4
• 2.2.5
• 2.2.6
• 2.2.7
• 2.2.8
• 2.2.9
• 2.2.10
• 2.2.11
• 2.2.12
• 2.2.13
• 2.2.14
• 2.2.15
• 2.2.16
• 2.2.17
• 2.2.18
• 2.2.19
• 3.1.0
• 3.1.1
• 3.1.2
• 3.1.3
• 3.1.4
• 3.1.5
• 3.1.6
• 3.1.7
• 3.1.8
• 3.1.9
• 3.1.10
• 3.1.11
• 3.1.12
• 3.1.13
• 3.1.14
• 3.1.15
• 3.1.16
• 3.1.17
• 3.2.0
• 3.2.1
• 3.2.2

License

• open-source

Website

• Product: https://github.com/rack/rack/

CPE 2.3info

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CPE 2.2info

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