Samba's use of Heimdal was vulnerable to a null pointer de-reference flaw due to missing sname in TGS-REQ. This is already fixed in upstream Heimdal via: https://github.com/heimdal/heimdal/commit/04171147948d0a3636bc6374181926f0fb2ec83a
Created samba tracking bugs for this issue: Affects: fedora-all [bug 2013081]