CVE-2026-34230

A flaw was found in Rack. An unauthenticated attacker can exploit a vulnerability in the Rack::Utils.selectbestencoding method by sending a specially crafted Accept-Encoding header with numerous wildcard entries. This leads to quadratic time complexity during processing, causing disproportionate...

GHSA-V569-HP3G-36WR 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...