CVE-2025-61771: Rack: Multipart parser buffers large non‑file fields entirely in memory, enabling DoS (memory exhaustion)

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).