Patching bash on old releases such as CentOS 5

You should be able to use the package manager to update the bash version. In some cases, if you want specific version of bash such as bash-3.2-33.el5_11.4, then you can download and instance using rpm

$wget http://mirror.centos.org/centos/5/updates/x86_64/RPMS/bash-3.2-33.el5_11.4.x86_64.rpm
$sudo rpm -ivh --force bash-3.2-33.el5_11.4.x86_64.rpm