buffer overflow on zsh-3.1.9

["Jonel Rienton" <nelski@xxxxxxxxxxxxxxxx>]

i would like to report a buffer overflow for zsh, procedures as follows:

1. hold down the alt key
2. while holding alt key press 9 six times
3 release both keys, hit any letter or number


result is a huge core file and a very high cpu load which almost bring down
my system.