Percona Server for MySQL 5.7.21-20 已发布，基于 MySQL 5.7.21，包含其中的所有错误修复。Percona Server for MySQL 5.7.21-20 是目前 5.7 系列的最新稳定版本。更新如下：
A new string variable
version_suffix allows to change suffix for the Percona Server version string returned by the read-only
version variable. Also
version_comment is converted from a global read-only to a global read-write variable.
keyring_vault_timeout variable allows to set the amount of seconds for the Vault server connection timeout. Bug fixed #298.
Build errors were present on FreeBSD (caused by fixing the bug #255 in Percona Server
5.6.38-83.0) and on MacOS (caused by fixing the bug #264 in Percona Server
5.7.20-19). Bugs fixed #2284 and #2286.
CMake error took place at compilation with bundled zlib. Bug fixed #302.
A GCC 7 warning fix introduced regression in Percona Server that led to a wrong SQL query built to access the remote server when Federated storage engine was used. Bug fixed #1134.
It was possible to enable
encrypt_binlog with no binary or relay logging enabled. Bug fixed #287.
Long buffer wait times where occurring on busy servers in case of the
IMPORT TABLESPACE command.
Bug fixed #276.
Server queries that contained JSON special characters and were logged by Audit Log Plugin in JSON format caused invalid output due to lack of escaping. Bug fixed #1115.
Percona Server now uses Travis CI for additional tests. Bug fixed #3777.
该版本包含对以下 CVE 漏洞的修复： CVE-2018-2565, CVE-2018-2573, CVE-2018-2576, CVE-2018-2583, CVE-2018-2586, CVE-2018-2590, CVE-2018-2612, CVE-2018-2600, CVE-2018-2622, CVE-2018-2640, CVE-2018-2645, CVE-2018-2646, CVE-2018-2647, CVE-2018-2665, CVE-2018-2667, CVE-2018-2668, CVE-2018-2696
MyRocks 和 TokuDB 也有变更，详细点此查看：https://www.percona.com/blog/2018/02/19/percona-server-mysql-5-7-21-20-now-available/