Current bash version is vulnerable to shellshock. But upgrading doesn't change the bash. I've tried rebooting.
CentOS version 5.6
[user@server ~]$ bash --version
GNU bash, version 3.2.25(1)-release (x86_64-redhat-linux-gnu)
Copyright (C) 2005 Free Software Foundation, Inc.
[user@server ~]$ yum list bash
Loaded plugins: fastestmirror
base/primary | 1.2 MB 00:00
base 3566/3566
Installed Packages
bash.x86_64 3.2-32.el5 installed