CVE-2008-2019
Simple Machines Forum (SMF), probably 1.1.4, relies on "randomly generated static" to hinder brute-force attacks on the WAV file (aka audio) CAPTCHA, which allows remote attackers to pass the CAPTCHA test via an automated attack that considers Hamming distances. NOTE: this issue reportedly exists because of an insufficient fix for CVE-2007-3308.
Date published : 2008-04-29
http://www.securityfocus.com/bid/28866
http://www.securityfocus.com/archive/1/491128/100/0/threaded