RHEL 4 / 5 / 6 : bash (RHSA-2014:1311)
Critical Nessus Plugin ID 79052
SynopsisThe remote Red Hat host is missing one or more security updates.
Description[Updated September 30, 2014] This advisory has been updated with information on restarting system services after applying this update.
No changes have been made to the original packages.
Updated bash packages that fix one security issue are now available for Red Hat Enterprise Linux 4 Extended Life Cycle Support, Red Hat Enterprise Linux 5.6 Long Life, Red Hat Enterprise Linux 5.9 Extended Update Support, Red Hat Enterprise Linux 6.2 Advanced Update Support, and Red Hat Enterprise Linux 6.4 Extended Update Support.
Red Hat Product Security has rated this update as having Important security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link in the References section.
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.
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.
SolutionUpdate the affected bash, bash-debuginfo and / or bash-doc packages.