It was found that, when the Sudo env_reset option was disabled (it is enabled by default), certain environment variables were not blacklisted as expected. A local user authorized to run commands using sudo could use this flaw to execute arbitrary code, allowing them to escalate their privileges.
This issue affects Sudo versions 1.6.9 to 1.8.4p5. Versions 1.8.5 and later are not affected.
Red Hat would like to thank Todd C. Miller for reporting this issue. Upstream acknowledges Sebastien Macke as the original reporter.
The "env_reset" option is enabled in the version of sudo as shipped with Red Hat Enterprise Linux 5, therefore this flaw does not affect the default configurations of the package.
This issue did not affect the version of sudo package as shipped with Red Hat Enterprise Linux 6.
This issue does not affect the version of sudo as shipped with Fedora 19 and Fedora 20.
Upstream fix: http://www.sudo.ws/repos/sudo/rev/748cefb49422
Note: This issue only has a security impact on configurations in which a user is permitted to run a limited number of commands with elevated privileges (for example, only commands to start/stop/restart a service). This issue has no impact on configurations in which users are permitted to run arbitrary commands with a target user's privileges.
This issue has been addressed in following products:
Red Hat Enterprise Linux 5
Via RHSA-2014:0266 https://rhn.redhat.com/errata/RHSA-2014-0266.html