Rack has quadratic complexity in Rack::Utils.select_best_encoding via wildcard Accept-Encoding header

Summary Rack::Utils.selectbestencoding processes Accept-Encoding values with quadratic time complexity when the header contains many wildcard entries. Because this method is used by Rack::Deflater to choose a response encoding, an unauthenticated attacker can send a single request with a crafted...

CVE-2026-34230

Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Utils.selectbestencoding processes Accept-Encoding values with quadratic time complexity when the header contains many wildcard entries. Because this method is used by Rack::Deflater to choose a respon...

CVE-2026-34230

Rack: Quadratic-time vulnerability in Rack::Utils.select_best_encoding when Accept-Encoding contains many wildcard entries. An unauthenticated attacker can craft a header to trigger disproportionate CPU usage on Rack::Deflater, causing DoS. Affected versions: < 2.2.23, < 3.1.21,

Rack has quadratic complexity in Rack::Utils.select_best_encoding via wildcard Accept-Encoding header

Summary Rack::Utils.selectbestencoding processes Accept-Encoding values with quadratic time complexity when the header contains many wildcard entries. Because this method is used by Rack::Deflater to choose a response encoding, an unauthenticated attacker can send a single request with a crafted...