Rack's multipart parser buffers large non‑file fields entirely in memory, enabling DoS (memory exhaustion)

Rack is a modular Ruby web server interface. In versions prior to 2.2.19, 3.1.17, and 3.2.2, ``Rack::Multipart::Parser` stores non-file form fields (parts without a `filename`) entirely in memory as Ruby `String` objects. A single large text field in a multipart/form-data request (hundreds of megabytes or more) can consume equivalent process memory, potentially leading to out-of-memory (OOM) conditions and denial of service (DoS). Attackers can send large non-file fields to trigger excessive memory usage. Impact scales with request size and concurrency, potentially leading to worker crashes or severe garbage-collection overhead. All Rack applications processing multipart form submissions are affected. Versions 2.2.19, 3.1.17, and 3.2.2 enforce a reasonable size cap for non-file fields (e.g., 2 MiB). Workarounds include restricting maximum request body size at the web-server or proxy layer (e.g., Nginx `client_max_body_size`) and validating and rejecting unusually large form fields at the application level.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

未加控制的资源消耗(资源穷尽)

Rack 资源管理错误漏洞

Rack是Rack开源的一个模块化的Ruby web服务器界面。 Rack 2.2.19之前版本、3.1.17之前版本和3.2.2之前版本存在资源管理错误漏洞，该漏洞源于Rack::Multipart::Parser将非文件表单字段完全存储在内存中，可能导致内存耗尽和拒绝服务攻击。

N/A

N/A