Percona Xtradb Cluster 5.5: node can't join cluster - SST fails with auth problem
I managed to perform SST by creating default user mysql@localhost without password on donor node, with required grants RELOAD, LOCK TABLES, REPLICATION CLIENT. Ugly workaround, but it worked.

On the next day I stopped mysql on node03 and started it after several minutes. SST started normally, with user and password from wsrep_sst_auth variable. Bug disappeared, I don't know what it was.