yum-rhn-plugin is vulnerable to privilege escalation. The vulnerability exists as it was discovered that yum-rhn-plugin did not verify the SSL certificate for all communication with a Red Hat Network server. An attacker able to redirect the network communication between a victim and an RHN server could use this flaw to provide malicious repository metadata. This metadata could be used to block the victim from receiving specific security updates.
secunia.com/advisories/31472
securitytracker.com/id?1020698
www.redhat.com/security/updates/classification/#moderate
www.redhat.com/support/errata/RHSA-2008-0815.html
www.securityfocus.com/bid/30695
access.redhat.com/errata/RHSA-2008:0815
bugzilla.redhat.com/show_bug.cgi?id=457113
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10864