Critical Bash Vulnerability Discovered – How to Test and Patch It Now

Linux Bash Vulnerability Exposes Serious Risk

Security Update

Today a critical Bash vulnerability was disclosed, requiring an urgent SSH Bash security patch. To test if your system is vulnerable, run the following command:

env x='() { :;}; echo vulnerable' bash -c "echo this is a test"

If the output shows vulnerable this is a test, the system is vulnerable and must be patched immediately. Apply the temporary fix by updating Bash: yum -y update bash After upgrading Bash, repeat the test:

env x='() { :;}; echo vulnerable' bash -c "echo this is a test"

The expected output should contain warnings such as bash: warning: x: ignoring function definition attempt followed by this is a test, indicating the vulnerability has been mitigated.

For more details, see the Red Hat security blog:

https://securityblog.redhat.com/2014/09/24/bash-specially-crafted-environment-variables-code-injection-attack/