An FR-GV-302 issue in FreeRADIUS 3.x before 3.0.15 allows "Infinite loop and memory exhaustion with 'concat' attributes" and a denial of service.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2017-2623
https://access.redhat.com/errata/RHSA-2017:2389
http://www.securityfocus.com/bid/99968