plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c in MIT Kerberos 5 (aka krb5) 1.12.x and 1.13.x before 1.13.1 when the KDC uses LDAP allows remote authenticated users to cause a denial of service (NULL pointer dereference and daemon crash) by creating a database entry for a keyless principal as demonstrated by a kadmin \add_principal -nokey\ or \purgekeys -all\ command.