The substr_compare function in string.c in PHP 5.1.2 allows context-dependent attackers to cause a denial of service (memory access violation) via an out-of-bounds offset argument.
http://secunia.com/advisories/20052
http://secunia.com/advisories/20269
http://secunia.com/advisories/20676
http://secunia.com/advisories/21125
http://security.gentoo.org/glsa/glsa-200605-08.xml
http://securitytracker.com/id?1015979
http://www.infigo.hr/en/in_focus/advisories/INFIGO-2006-04-02
http://www.mandriva.com/security/advisories?name=MDKSA-2006:091
http://www.novell.com/linux/security/advisories/2006_31_php.html
http://www.ubuntu.com/usn/usn-320-1