This command will show you if your bash is vulnerable.

# env x='() { :;}; echo vulnerable’ bash -c “echo not vulnerable”
If you get ” vulnerable ” then you need to upgrade and if you get ” not vulnerable” then you are safe.

If your server is vulnerable then you can take these steps to resolve.

CentOs, Fedora, Redhat

yum update bash

Debian and ubuntu

apt-get install –only-upgrade bash