The GNU Bourne Again shell (Bash) is a shell and command language interpreter compatible with the Bourne shell (sh). Bash is the default shell for Red Hat Enterprise Linux.
It was found that the fix for CVE-2014-6271 was incomplete, and Bash still allowed certain characters to be injected into other environments via specially crafted environment variables. An attacker could potentially use this flaw to override or bypass environment restrictions to execute shell commands. Certain services and applications allow remote unauthenticated attackers to provide environment variables, allowing them to exploit this issue. (CVE-2014-7169)
Applications which directly create bash functions as environment variables need to be made aware of changes to the way names are handled by this update. Note that certain services, screen sessions, and tmux sessions may need to be restarted, and affected interactive users may need to re-login. Installing these updated packages without restarting services will address the vulnerability, but functionality may be impacted until affected services are restarted. For more information see the Knowledgebase article at https://access.redhat.com/articles/1200223
Note: Docker users are advised to use "yum update" within their containers, and to commit the resulting changes.
For additional information on CVE-2014-6271 and CVE-2014-7169, refer to the aforementioned Knowledgebase article.
All bash users are advised to upgrade to these updated packages, which contain a backported patch to correct this issue.