Apparently this affects not just RHEL but CentOS, OSX and many others. Apache + CGI calls too:
https://access.redhat.com/articles/1200223
Patch Bash NOW: 'Shell Shock' bug blasts OS X, Linux systems wide open • The Register
https://access.redhat.com/articles/1200223
Patch Bash NOW: 'Shell Shock' bug blasts OS X, Linux systems wide open • The Register