etc-update in Portage before 2.1.3.11 on Gentoo Linux relies on the umask to set permissions for the merge file, often resulting in permissions weaker than those of the original files, which might allow local users to obtain sensitive information by reading the merge file.
https://exchange.xforce.ibmcloud.com/vulnerabilities/39035
http://www.securitytracker.com/id?1019097
http://www.securityfocus.com/bid/26864
http://www.gentoo.org/security/en/glsa/glsa-200712-11.xml