Comment 1 for bug 1623040

Got same issue:
Server:
 echo "status"|mysql|grep Server
Server version: 5.7.14-7 Percona Server (GPL), Release 7, Revision 083e298
uname -a
Linux 4.4.20-1.el7.elrepo.x86_64 #1 SMP Wed Sep 7 11:44:03 EDT 2016 x86_64 x86_64 x86_64 GNU/Linux

mysql> create table test1 (id int);
inQuery OK, 0 rows affected (1.56 sec)

mysql> insert into test1 set id=2;
Query OK, 1 row affected (0.27 sec)

Newer client:
# mysql -V
mysql Ver 14.14 Distrib 5.7.17, for FreeBSD10.1 (amd64) using EditLine wrapper
mysql> select * from test1 where id=2;
--------------
select * from test1 where id=2
--------------

+------+
| id |
+------+
| 2 |
+------+
1 row in set (0.00 sec)

Older client:
mysql -V
mysql Ver 14.14 Distrib 5.6.24, for FreeBSD10.1 (amd64) using 5.2
mysql> select * from test1 where id=2;
--------------
select * from test1 where id=2
--------------

ERROR 2027 (HY000): Malformed packet

if run older client first:
mysql -V
mysql Ver 14.14 Distrib 5.6.24, for FreeBSD10.1 (amd64) using 5.2
mysql> select * from test1 where id='2';
--------------
select * from test1 where id='2'
--------------

+------+
| id |
+------+
| 2 |
+------+
1 row in set (0.01 sec)

Newer client got warnings message and disconnects:
mysql -V
mysql Ver 14.14 Distrib 5.7.17, for FreeBSD10.1 (amd64) using EditLine wrapper
mysql> select * from test1 where id='2';
--------------
select * from test1 where id='2'
--------------

Empty set, 28160 warnings (0.00 sec)

mysql> show warnigs;
--------------
show warnigs
--------------

ERROR 2013 (HY000): Lost connection to MySQL server during query

Server query_cache_settings:
mysql> show variables like "query_cache_%";
+------------------------------+---------+
| Variable_name | Value |
+------------------------------+---------+
| query_cache_limit | 1048576 |
| query_cache_min_res_unit | 4096 |
| query_cache_size | 1048576 |
| query_cache_strip_comments | OFF |
| query_cache_type | ON |
| query_cache_wlock_invalidate | OFF |
+------------------------------+---------+
6 rows in set (0.00 sec)

mysql>

How to reproduce: install percona server 5.7.15(or 5.7.16), turn query_cache on, select via 5.6 client,then same query via 5.7 client.

Config file:
cat /etc/my.cnf|egrep -v '^[[:space:]]*#'

[mysqld]
join_buffer_size = 128M
sort_buffer_size = 2M
read_rnd_buffer_size = 2M
query_cache_type=1
datadir=/data/mysql
socket=/tmp/mysql.sock

symbolic-links=0

log-error=/spool/logs/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

innodb_lock_wait_timeout = 15
innodb_max_dirty_pages_pct = 90
innodb_stats_sample_pages = 32

init-connect="SET NAMES cp1251"
collation-server=cp1251_general_ci
character-set-server=cp1251

[mysql]
socket=/tmp/mysql.sock
user=root
default-character-set=cp1251