Red Hat Certificate System (RHCS) 7.3 and 8 and Dogtag Certificate System do not require authentication for requests to decrypt SCEP one-time PINs, which allows remote attackers to obtain PINs by sniffing the network for SCEP requests and then sending decryption requests to the Certificate Authority component.
https://rhn.redhat.com/errata/RHSA-2010-0838.html
https://rhn.redhat.com/errata/RHSA-2010-0837.html
https://fedorahosted.org/pki/changeset/1261
https://bugzilla.redhat.com/show_bug.cgi?id=648882