rack: Rack's unbounded multipart preamble buffering enables DoS (memory exhaustion)

A flaw was found in Rack where the Rack::Multipart::Parser buffers the multipart preamble memory without size limits. A remote attacker can send a crafted multipart/form-data request with a very large preamble before its first boundary, causing excessive memory consumption and denial of service...

CVE-2025-61770

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 buffers the entire multipart preamble bytes before the first boundary in memory without any size limit. A client can send a large preamble followed by a valid boundary, causing...