The installUpdates function in yum-cron/yum-cron.py in yum 3.4.3 and earlier does not properly check the return value of the sigCheckPkg function, which allows remote attackers to bypass the RMP package signing restriction via an unsigned package.
https://bugzilla.redhat.com/show_bug.cgi?id=1057377
https://bugzilla.redhat.com/show_bug.cgi?id=1052440
http://yum.baseurl.org/gitweb?p=yum.git%3Ba=commitdiff%3Bh=9df69e5794