The iconv_substr function in PHP 5.2.4 and earlier allows context-dependent attackers to cause (1) a denial of service (application crash) via a long string in the charset parameter, probably also requiring a long string in the str parameter; or (2) a denial of service (temporary application hang) via a long string in the str parameter. NOTE: this might not be a vulnerability in most web server environments that support multiple threads, unless these issues can be demonstrated for code execution.
https://issues.rpath.com/browse/RPL-1943
http://www.securityfocus.com/archive/1/491693/100/0/threaded
http://www.securityfocus.com/archive/1/478637/100/0/threaded
http://www.gentoo.org/security/en/glsa/glsa-200710-02.xml
http://wiki.rpath.com/wiki/Advisories:rPSA-2007-0242
http://securityreason.com/securityalert/3115
http://secunia.com/advisories/30040
http://secunia.com/advisories/27659