diff --git a/sql/auth/sql_authentication.cc b/sql/auth/sql_authentication.cc
--- a/sql/auth/sql_authentication.cc
+++ b/sql/auth/sql_authentication.cc
@@ -1116,6 +1116,7 @@ static bool parse_com_change_user_packet(MPVIO_EXT *mpvio, size_t packet_length)
       my_message(ER_UNKNOWN_COM_ERROR, ER(ER_UNKNOWN_COM_ERROR), MYF(0));
       DBUG_RETURN(1);
     }
+    ptr = ptr + 2 + strlen(client_plugin) + 1;
   }
   else
     client_plugin= native_password_plugin_name.str;