HTTP::Body versions before 1.24_02 for Perl parse the trailer in quadratic time. Everything after the last chunk in the same call to add() is parsed with HTTP::Headers, which takes time quadratic in the number of fields of one name. For example, it takes several seconds to parse 16 KiB of "a:" lines. A remote attackercan exhause the CPU with a single request. HTTP::Body version 1.25 limits the size and number of lines in the trailer.