GNU Bash through 4.3 bash43-026 does not properly parse function definitions in the values of environment variables, which allows remote attackers to execute arbitrary code or cause a denial of service (uninitialized memory access, and untrusted-pointer read and write operations) via a crafted environment, as demonstrated by vectors involving the ForceCommand feature in OpenSSH sshd, the mod_cgi and mod_cgid modules in the Apache HTTP Server, scripts executed by unspecified DHCP clients, and other situations in which setting the environment occurs across a privilege boundary from Bash execution. NOTE: this vulnerability exists because of an incomplete fix for CVE-2014-6271 and CVE-2014-7169.

Affected: Ubuntu:14.04:LTS: bash

Michal Zalewski discovered that Bash incorrectly handled parsing certain function definitions. If an attacker were able to create an environment variable containing a function definition with a very specific name, these issues could possibly be used to bypass certain environment restrictions and execute arbitrary code. (CVE-2014-6277, CVE-2014-6278)

Please note that the previous Bash security update, USN-2364-1, includes a hardening measure that prevents these issues from being used in a Shellshock attack.