File System Permissions
If you've given users the ability to write to your mysql database directory, you've already pissed up. A sane setup should be protected from that by default. Never write anything in to the same directory that someone else can, too many opportunities for race conditions and other timing attacks.
The heap and stack attack look like they could be kind of dangerous, hack in a poorly protected site on your server, get credentials to your sql server, then dump password tables for other sites. Could see a few more big sites password lists get in the wild from this.