CVE-2025-61919: Rack is vulnerable to a memory-exhaustion DoS through unbounded URL-encoded

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`).

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

rack rack

< 2.2.20affected
>= 3.0, < 3.1.18affected
>= 3.2, < 3.2.3affected

CVE-2025-61919

Rack is vulnerable to a memory-exhaustion DoS through unbounded URL-encoded body parsing

Description

Affected products

rack rack

References