一、描述
漏扫发现MySQL有低风险漏洞，自己写方案、自己做测试、自己升级。
版本：MySQL 5.7.25 升级到MySQL 5.7.28最新版本。
架构：主从架构
二、升级流程
1、下载最新版数据库软件MySQL 5.7.28
2、上传到指定目录
3、备份数据库软件、数据库数据目录、my.cnf
4、解压缩数据库软件到指定路径
5、关闭备库
6、使用新版软件启动备库，mysqld_safe &
7、登录备库，发现版本已升级，使用mysql_upgrade命令升级系统数据库
8、无报错的话，重启备库。
9、主库按照备库流程走一遍
10、最后确认主备库是否一致
三、部分内容
# mysql_upgrade -uroot -p
mysql_upgrade: [Warning] Using a password on the command line interface can be insecure.
Checking if update is needed.
Checking server version.
Running queries to upgrade MySQL server.
Checking system database.
mysql.columns_priv                                 OK
mysql.db                                           OK
mysql.engine_cost                                  OK
mysql.event                                        OK
mysql.func                                         OK
mysql.general_log                                  OK
mysql.gtid_executed                                OK
mysql.help_category                                OK
mysql.help_keyword                                 OK
mysql.help_relation                                OK
mysql.help_topic                                   OK
mysql.innodb_index_stats                           OK
mysql.innodb_table_stats                           OK
mysql.ndb_binlog_index                             OK
mysql.plugin                                       OK
mysql.proc                                         OK
mysql.procs_priv                                   OK
mysql.proxies_priv                                 OK
mysql.server_cost                                  OK
mysql.servers                                      OK
mysql.slave_master_info                            OK
mysql.slave_relay_log_info                         OK
mysql.slave_worker_info                            OK
mysql.slow_log                                     OK
mysql.tables_priv                                  OK
mysql.time_zone                                    OK
mysql.time_zone_leap_second                        OK
mysql.time_zone_name                               OK
mysql.time_zone_transition                         OK
mysql.time_zone_transition_type                    OK
mysql.user                                         OK
Found outdated sys schema version 1.5.1.
Upgrading the sys schema.
Checking databases.
sys.sys_config                                     OK
Upgrade process completed successfully.
Checking if update is needed.

mysql> status
--------------
mysql  Ver 14.14 Distrib 5.7.28, for linux-glibc2.12 (x86_64) using  EditLine wrapper

Connection id:      2
Current database:   
Current user:       root@localhost
SSL:            Not in use
Current pager:      stdout
Using outfile:      ''
Using delimiter:    ;
Server version:     5.7.28-log MySQL Community Server (GPL)
Protocol version:   10
Connection:     Localhost via UNIX socket
Server characterset:    utf8mb4
Db     characterset:    utf8mb4
Client characterset:    utf8mb4
Conn.  characterset:    utf8mb4
UNIX socket:        /tmp/mysql.sock
Uptime:         27 sec