GNU Bash (Bourne Again SHell) is a command shell commonly used on Linux and Unix systems.
CUPS is printing software for UNIX-like systems that allows a computer to act as a print server.
The Bash shell executes commands injected after function definitions contained in environment variables. This could be used by a remote attacker to cause arbitrary commands to execute when a CUPS server invokes the Bash shell.
Apply updated Bash packages from the Linux or Unix vendor.
This exploit requires the user name and password for the CUPS server. This attack vector may not exist on all systems with affected versions of Bash, and other attack vectors may exist which are not covered by this exploit.