Double free vulnerability in the authentication and authentication token alteration code in PAM-MySQL 0.6.x before 0.6.2 and 0.7.x before 0.7pre3 allows remote attackers to cause a denial of service (application crash) and possibly execute arbitrary code via crafted passwords, which lead to a double free of a pointer that was created by the pam_get_item function. NOTE: this issue only occurs in certain configurations in which there are multiple PAM modules, PAM-MySQL is not evaluated first, and there are no requisite modules before PAM-MySQL.
http://www.vupen.com/english/advisories/2006/0490
http://www.securityfocus.com/bid/16564
http://www.kb.cert.org/vuls/id/693909
http://www.gentoo.org/security/en/glsa/glsa-200606-18.xml
http://sourceforge.net/forum/forum.php?forum_id=499394
http://securitytracker.com/id?1015603
http://secunia.com/advisories/20690