CVE-2025-61772: Rack's multipart parser buffers unbounded per-part headers, enabling DoS (memory exhaustion)

Rack::Multipart::Parser can accumulate unbounded data when a multipart part’s header block never terminates with the required blank line (CRLFCRLF). The parser keeps appending incoming bytes to memory without a size cap, allowing a remote attacker to exhaust memory and cause a denial of service (DoS).