diff --git a/mysql-test/include/ctype_ident_sys.inc b/mysql-test/include/ctype_ident_sys.inc
new file mode 100644
index 00000000000..80ac962f031
--- /dev/null
+++ b/mysql-test/include/ctype_ident_sys.inc
@@ -0,0 +1,73 @@
+--echo #
+--echo # SET STATEMENT (bad|good.bad|bad.good)=1
+--echo #
+
+--error ER_INVALID_CHARACTER_STRING
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT ',@seq, '=1 SELECT 1');
+
+--error ER_INVALID_CHARACTER_STRING
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT ',@seq, '.a=1 SELECT 1');
+
+--error ER_INVALID_CHARACTER_STRING
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT a.',@seq, '=1 SELECT 1');
+
+
+--echo #
+--echo # SET SESSION (bad|good.bad|bad.good)=1
+--echo #
+
+--error ER_INVALID_CHARACTER_STRING
+EXECUTE IMMEDIATE CONCAT('SET SESSION ',@seq, '=1 SELECT 1');
+
+--error ER_INVALID_CHARACTER_STRING
+EXECUTE IMMEDIATE CONCAT('SET SESSION ',@seq, '.a=1 SELECT 1');
+
+--error ER_INVALID_CHARACTER_STRING
+EXECUTE IMMEDIATE CONCAT('SET SESSION a.',@seq, '=1 SELECT 1');
+
+
+--echo #
+--echo # SET (bad|good.bad|bad.good)=1
+--echo #
+
+
+--error ER_INVALID_CHARACTER_STRING
+EXECUTE IMMEDIATE CONCAT('SET ', @seq, '=1');
+
+--error ER_INVALID_CHARACTER_STRING
+EXECUTE IMMEDIATE CONCAT('SET ', @seq, '.a=1');
+
+--error ER_INVALID_CHARACTER_STRING
+EXECUTE IMMEDIATE CONCAT('SET a.', @seq, '=1');
+
+
+--echo #
+--echo # Oracle SP call: BEGIN (bad|good.bad|bad.good)(params); END
+--echo #
+
+SET sql_mode=ORACLE;
+--error ER_INVALID_CHARACTER_STRING
+EXECUTE IMMEDIATE CONCAT('BEGIN ',@seq, '(1); END;');
+
+--error ER_INVALID_CHARACTER_STRING
+EXECUTE IMMEDIATE CONCAT('BEGIN ',@seq, '.a(1); END;');
+
+--error ER_INVALID_CHARACTER_STRING
+EXECUTE IMMEDIATE CONCAT('BEGIN a.',@seq, '(1); END;');
+
+
+--echo #
+--echo # Oracle assignment: (bad|good.bad|bad.good):= value
+--echo #
+
+--error ER_INVALID_CHARACTER_STRING
+EXECUTE IMMEDIATE CONCAT(@seq, ':=1');
+
+--error ER_INVALID_CHARACTER_STRING
+EXECUTE IMMEDIATE CONCAT(@seq, '.a:=1');
+
+--error ER_INVALID_CHARACTER_STRING
+EXECUTE IMMEDIATE CONCAT('a.', @seq, ':=1');
+
+
+SET sql_mode=DEFAULT;
diff --git a/mysql-test/main/ctype_big5.result b/mysql-test/main/ctype_big5.result
index 95d1f10349e..41ce8f0b82e 100644
--- a/mysql-test/main/ctype_big5.result
+++ b/mysql-test/main/ctype_big5.result
@@ -5384,3 +5384,61 @@ SET DEFAULT_STORAGE_ENGINE=Default;
 #
 # End of 10.2 tests
 #
+#
+# Start of 10.5 tests
+#
+#
+# MDEV-22625 SIGSEGV in intern_find_sys_var (optimized builds)
+#
+SET NAMES big5;
+SET @seq=_big5 0xA3C0;
+#
+# SET STATEMENT (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT ',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid big5 character string: '\xA3\xC0'
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT ',@seq, '.a=1 SELECT 1');
+ERROR HY000: Invalid big5 character string: '\xA3\xC0'
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT a.',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid big5 character string: '\xA3\xC0'
+#
+# SET SESSION (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET SESSION ',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid big5 character string: '\xA3\xC0'
+EXECUTE IMMEDIATE CONCAT('SET SESSION ',@seq, '.a=1 SELECT 1');
+ERROR HY000: Invalid big5 character string: '\xA3\xC0'
+EXECUTE IMMEDIATE CONCAT('SET SESSION a.',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid big5 character string: '\xA3\xC0'
+#
+# SET (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET ', @seq, '=1');
+ERROR HY000: Invalid big5 character string: '\xA3\xC0'
+EXECUTE IMMEDIATE CONCAT('SET ', @seq, '.a=1');
+ERROR HY000: Invalid big5 character string: '\xA3\xC0'
+EXECUTE IMMEDIATE CONCAT('SET a.', @seq, '=1');
+ERROR HY000: Invalid big5 character string: '\xA3\xC0'
+#
+# Oracle SP call: BEGIN (bad|good.bad|bad.good)(params); END
+#
+SET sql_mode=ORACLE;
+EXECUTE IMMEDIATE CONCAT('BEGIN ',@seq, '(1); END;');
+ERROR HY000: Invalid big5 character string: '\xA3\xC0'
+EXECUTE IMMEDIATE CONCAT('BEGIN ',@seq, '.a(1); END;');
+ERROR HY000: Invalid big5 character string: '\xA3\xC0'
+EXECUTE IMMEDIATE CONCAT('BEGIN a.',@seq, '(1); END;');
+ERROR HY000: Invalid big5 character string: '\xA3\xC0'
+#
+# Oracle assignment: (bad|good.bad|bad.good):= value
+#
+EXECUTE IMMEDIATE CONCAT(@seq, ':=1');
+ERROR HY000: Invalid big5 character string: '\xA3\xC0'
+EXECUTE IMMEDIATE CONCAT(@seq, '.a:=1');
+ERROR HY000: Invalid big5 character string: '\xA3\xC0'
+EXECUTE IMMEDIATE CONCAT('a.', @seq, ':=1');
+ERROR HY000: Invalid big5 character string: '\xA3\xC0'
+SET sql_mode=DEFAULT;
+#
+# End of 10.5 tests
+#
diff --git a/mysql-test/main/ctype_big5.test b/mysql-test/main/ctype_big5.test
index 410203c7c86..41991258886 100644
--- a/mysql-test/main/ctype_big5.test
+++ b/mysql-test/main/ctype_big5.test
@@ -269,3 +269,20 @@ let $coll_pad='big5_bin';
 --echo #
 --echo # End of 10.2 tests
 --echo #
+
+
+--echo #
+--echo # Start of 10.5 tests
+--echo #
+
+--echo #
+--echo # MDEV-22625 SIGSEGV in intern_find_sys_var (optimized builds)
+--echo #
+
+SET NAMES big5;
+SET @seq=_big5 0xA3C0;
+--source include/ctype_ident_sys.inc
+
+--echo #
+--echo # End of 10.5 tests
+--echo #
diff --git a/mysql-test/main/ctype_cp932.result b/mysql-test/main/ctype_cp932.result
index dcb94d95c50..952130cf11c 100644
--- a/mysql-test/main/ctype_cp932.result
+++ b/mysql-test/main/ctype_cp932.result
@@ -597,3 +597,61 @@ SET DEFAULT_STORAGE_ENGINE=Default;
 #
 # End of 10.2 tests
 #
+#
+# Start of 10.5 tests
+#
+#
+# MDEV-22625 SIGSEGV in intern_find_sys_var (optimized builds)
+#
+SET NAMES cp932;
+SET @seq=_cp932 0x81AD;
+#
+# SET STATEMENT (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT ',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid cp932 character string: '\x81\xAD'
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT ',@seq, '.a=1 SELECT 1');
+ERROR HY000: Invalid cp932 character string: '\x81\xAD'
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT a.',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid cp932 character string: '\x81\xAD'
+#
+# SET SESSION (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET SESSION ',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid cp932 character string: '\x81\xAD'
+EXECUTE IMMEDIATE CONCAT('SET SESSION ',@seq, '.a=1 SELECT 1');
+ERROR HY000: Invalid cp932 character string: '\x81\xAD'
+EXECUTE IMMEDIATE CONCAT('SET SESSION a.',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid cp932 character string: '\x81\xAD'
+#
+# SET (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET ', @seq, '=1');
+ERROR HY000: Invalid cp932 character string: '\x81\xAD'
+EXECUTE IMMEDIATE CONCAT('SET ', @seq, '.a=1');
+ERROR HY000: Invalid cp932 character string: '\x81\xAD'
+EXECUTE IMMEDIATE CONCAT('SET a.', @seq, '=1');
+ERROR HY000: Invalid cp932 character string: '\x81\xAD'
+#
+# Oracle SP call: BEGIN (bad|good.bad|bad.good)(params); END
+#
+SET sql_mode=ORACLE;
+EXECUTE IMMEDIATE CONCAT('BEGIN ',@seq, '(1); END;');
+ERROR HY000: Invalid cp932 character string: '\x81\xAD'
+EXECUTE IMMEDIATE CONCAT('BEGIN ',@seq, '.a(1); END;');
+ERROR HY000: Invalid cp932 character string: '\x81\xAD'
+EXECUTE IMMEDIATE CONCAT('BEGIN a.',@seq, '(1); END;');
+ERROR HY000: Invalid cp932 character string: '\x81\xAD'
+#
+# Oracle assignment: (bad|good.bad|bad.good):= value
+#
+EXECUTE IMMEDIATE CONCAT(@seq, ':=1');
+ERROR HY000: Invalid cp932 character string: '\x81\xAD'
+EXECUTE IMMEDIATE CONCAT(@seq, '.a:=1');
+ERROR HY000: Invalid cp932 character string: '\x81\xAD'
+EXECUTE IMMEDIATE CONCAT('a.', @seq, ':=1');
+ERROR HY000: Invalid cp932 character string: '\x81\xAD'
+SET sql_mode=DEFAULT;
+#
+# End of 10.5 tests
+#
diff --git a/mysql-test/main/ctype_cp932.test b/mysql-test/main/ctype_cp932.test
index 2486ca8a79e..0f5ff437d33 100644
--- a/mysql-test/main/ctype_cp932.test
+++ b/mysql-test/main/ctype_cp932.test
@@ -47,3 +47,20 @@ let $coll_pad='cp932_bin';
 --echo #
 --echo # End of 10.2 tests
 --echo #
+
+
+--echo #
+--echo # Start of 10.5 tests
+--echo #
+
+--echo #
+--echo # MDEV-22625 SIGSEGV in intern_find_sys_var (optimized builds)
+--echo #
+
+SET NAMES cp932;
+SET @seq=_cp932 0x81AD;
+--source include/ctype_ident_sys.inc
+
+--echo #
+--echo # End of 10.5 tests
+--echo #
diff --git a/mysql-test/main/ctype_dec8.result b/mysql-test/main/ctype_dec8.result
new file mode 100644
index 00000000000..f0522494bb2
--- /dev/null
+++ b/mysql-test/main/ctype_dec8.result
@@ -0,0 +1,58 @@
+#
+# Start of 10.5 tests
+#
+#
+# MDEV-22625 SIGSEGV in intern_find_sys_var (optimized builds)
+#
+SET NAMES dec8;
+SET @seq=_dec8 0xD0;
+#
+# SET STATEMENT (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT ',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid dec8 character string: '\xD0'
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT ',@seq, '.a=1 SELECT 1');
+ERROR HY000: Invalid dec8 character string: '\xD0'
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT a.',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid dec8 character string: '\xD0'
+#
+# SET SESSION (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET SESSION ',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid dec8 character string: '\xD0'
+EXECUTE IMMEDIATE CONCAT('SET SESSION ',@seq, '.a=1 SELECT 1');
+ERROR HY000: Invalid dec8 character string: '\xD0'
+EXECUTE IMMEDIATE CONCAT('SET SESSION a.',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid dec8 character string: '\xD0'
+#
+# SET (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET ', @seq, '=1');
+ERROR HY000: Invalid dec8 character string: '\xD0'
+EXECUTE IMMEDIATE CONCAT('SET ', @seq, '.a=1');
+ERROR HY000: Invalid dec8 character string: '\xD0'
+EXECUTE IMMEDIATE CONCAT('SET a.', @seq, '=1');
+ERROR HY000: Invalid dec8 character string: '\xD0'
+#
+# Oracle SP call: BEGIN (bad|good.bad|bad.good)(params); END
+#
+SET sql_mode=ORACLE;
+EXECUTE IMMEDIATE CONCAT('BEGIN ',@seq, '(1); END;');
+ERROR HY000: Invalid dec8 character string: '\xD0'
+EXECUTE IMMEDIATE CONCAT('BEGIN ',@seq, '.a(1); END;');
+ERROR HY000: Invalid dec8 character string: '\xD0'
+EXECUTE IMMEDIATE CONCAT('BEGIN a.',@seq, '(1); END;');
+ERROR HY000: Invalid dec8 character string: '\xD0'
+#
+# Oracle assignment: (bad|good.bad|bad.good):= value
+#
+EXECUTE IMMEDIATE CONCAT(@seq, ':=1');
+ERROR HY000: Invalid dec8 character string: '\xD0'
+EXECUTE IMMEDIATE CONCAT(@seq, '.a:=1');
+ERROR HY000: Invalid dec8 character string: '\xD0'
+EXECUTE IMMEDIATE CONCAT('a.', @seq, ':=1');
+ERROR HY000: Invalid dec8 character string: '\xD0'
+SET sql_mode=DEFAULT;
+#
+# End of 10.5 tests
+#
diff --git a/mysql-test/main/ctype_dec8.test b/mysql-test/main/ctype_dec8.test
new file mode 100644
index 00000000000..869d6242225
--- /dev/null
+++ b/mysql-test/main/ctype_dec8.test
@@ -0,0 +1,15 @@
+--echo #
+--echo # Start of 10.5 tests
+--echo #
+
+--echo #
+--echo # MDEV-22625 SIGSEGV in intern_find_sys_var (optimized builds)
+--echo #
+
+SET NAMES dec8;
+SET @seq=_dec8 0xD0;
+--source include/ctype_ident_sys.inc
+
+--echo #
+--echo # End of 10.5 tests
+--echo #
diff --git a/mysql-test/main/ctype_eucjpms.result b/mysql-test/main/ctype_eucjpms.result
index 1a40490308e..ba91abca96f 100644
--- a/mysql-test/main/ctype_eucjpms.result
+++ b/mysql-test/main/ctype_eucjpms.result
@@ -34491,3 +34491,61 @@ SET DEFAULT_STORAGE_ENGINE=Default;
 #
 # End of 10.2 tests
 #
+#
+# Start of 10.5 tests
+#
+#
+# MDEV-22625 SIGSEGV in intern_find_sys_var (optimized builds)
+#
+SET NAMES eucjpms;
+SET @seq=_eucjpms 0x8FA1A1;
+#
+# SET STATEMENT (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT ',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid eucjpms character string: '\x8F\xA1\xA1'
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT ',@seq, '.a=1 SELECT 1');
+ERROR HY000: Invalid eucjpms character string: '\x8F\xA1\xA1'
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT a.',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid eucjpms character string: '\x8F\xA1\xA1'
+#
+# SET SESSION (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET SESSION ',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid eucjpms character string: '\x8F\xA1\xA1'
+EXECUTE IMMEDIATE CONCAT('SET SESSION ',@seq, '.a=1 SELECT 1');
+ERROR HY000: Invalid eucjpms character string: '\x8F\xA1\xA1'
+EXECUTE IMMEDIATE CONCAT('SET SESSION a.',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid eucjpms character string: '\x8F\xA1\xA1'
+#
+# SET (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET ', @seq, '=1');
+ERROR HY000: Invalid eucjpms character string: '\x8F\xA1\xA1'
+EXECUTE IMMEDIATE CONCAT('SET ', @seq, '.a=1');
+ERROR HY000: Invalid eucjpms character string: '\x8F\xA1\xA1'
+EXECUTE IMMEDIATE CONCAT('SET a.', @seq, '=1');
+ERROR HY000: Invalid eucjpms character string: '\x8F\xA1\xA1'
+#
+# Oracle SP call: BEGIN (bad|good.bad|bad.good)(params); END
+#
+SET sql_mode=ORACLE;
+EXECUTE IMMEDIATE CONCAT('BEGIN ',@seq, '(1); END;');
+ERROR HY000: Invalid eucjpms character string: '\x8F\xA1\xA1'
+EXECUTE IMMEDIATE CONCAT('BEGIN ',@seq, '.a(1); END;');
+ERROR HY000: Invalid eucjpms character string: '\x8F\xA1\xA1'
+EXECUTE IMMEDIATE CONCAT('BEGIN a.',@seq, '(1); END;');
+ERROR HY000: Invalid eucjpms character string: '\x8F\xA1\xA1'
+#
+# Oracle assignment: (bad|good.bad|bad.good):= value
+#
+EXECUTE IMMEDIATE CONCAT(@seq, ':=1');
+ERROR HY000: Invalid eucjpms character string: '\x8F\xA1\xA1'
+EXECUTE IMMEDIATE CONCAT(@seq, '.a:=1');
+ERROR HY000: Invalid eucjpms character string: '\x8F\xA1\xA1'
+EXECUTE IMMEDIATE CONCAT('a.', @seq, ':=1');
+ERROR HY000: Invalid eucjpms character string: '\x8F\xA1\xA1'
+SET sql_mode=DEFAULT;
+#
+# End of 10.5 tests
+#
diff --git a/mysql-test/main/ctype_eucjpms.test b/mysql-test/main/ctype_eucjpms.test
index 867ca809dbf..6af72270853 100644
--- a/mysql-test/main/ctype_eucjpms.test
+++ b/mysql-test/main/ctype_eucjpms.test
@@ -596,3 +596,20 @@ let $coll_pad='eucjpms_bin';
 --echo #
 --echo # End of 10.2 tests
 --echo #
+
+
+--echo #
+--echo # Start of 10.5 tests
+--echo #
+
+--echo #
+--echo # MDEV-22625 SIGSEGV in intern_find_sys_var (optimized builds)
+--echo #
+
+SET NAMES eucjpms;
+SET @seq=_eucjpms 0x8FA1A1;
+--source include/ctype_ident_sys.inc
+
+--echo #
+--echo # End of 10.5 tests
+--echo #
diff --git a/mysql-test/main/ctype_euckr.result b/mysql-test/main/ctype_euckr.result
index 9f98e39c59e..5bfcc7071f3 100644
--- a/mysql-test/main/ctype_euckr.result
+++ b/mysql-test/main/ctype_euckr.result
@@ -26009,3 +26009,61 @@ SET DEFAULT_STORAGE_ENGINE=Default;
 #
 # End of 10.2 tests
 #
+#
+# Start of 10.5 tests
+#
+#
+# MDEV-22625 SIGSEGV in intern_find_sys_var (optimized builds)
+#
+SET NAMES euckr;
+SET @seq=_euckr 0xA2E8;
+#
+# SET STATEMENT (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT ',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid euckr character string: '\xA2\xE8'
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT ',@seq, '.a=1 SELECT 1');
+ERROR HY000: Invalid euckr character string: '\xA2\xE8'
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT a.',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid euckr character string: '\xA2\xE8'
+#
+# SET SESSION (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET SESSION ',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid euckr character string: '\xA2\xE8'
+EXECUTE IMMEDIATE CONCAT('SET SESSION ',@seq, '.a=1 SELECT 1');
+ERROR HY000: Invalid euckr character string: '\xA2\xE8'
+EXECUTE IMMEDIATE CONCAT('SET SESSION a.',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid euckr character string: '\xA2\xE8'
+#
+# SET (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET ', @seq, '=1');
+ERROR HY000: Invalid euckr character string: '\xA2\xE8'
+EXECUTE IMMEDIATE CONCAT('SET ', @seq, '.a=1');
+ERROR HY000: Invalid euckr character string: '\xA2\xE8'
+EXECUTE IMMEDIATE CONCAT('SET a.', @seq, '=1');
+ERROR HY000: Invalid euckr character string: '\xA2\xE8'
+#
+# Oracle SP call: BEGIN (bad|good.bad|bad.good)(params); END
+#
+SET sql_mode=ORACLE;
+EXECUTE IMMEDIATE CONCAT('BEGIN ',@seq, '(1); END;');
+ERROR HY000: Invalid euckr character string: '\xA2\xE8'
+EXECUTE IMMEDIATE CONCAT('BEGIN ',@seq, '.a(1); END;');
+ERROR HY000: Invalid euckr character string: '\xA2\xE8'
+EXECUTE IMMEDIATE CONCAT('BEGIN a.',@seq, '(1); END;');
+ERROR HY000: Invalid euckr character string: '\xA2\xE8'
+#
+# Oracle assignment: (bad|good.bad|bad.good):= value
+#
+EXECUTE IMMEDIATE CONCAT(@seq, ':=1');
+ERROR HY000: Invalid euckr character string: '\xA2\xE8'
+EXECUTE IMMEDIATE CONCAT(@seq, '.a:=1');
+ERROR HY000: Invalid euckr character string: '\xA2\xE8'
+EXECUTE IMMEDIATE CONCAT('a.', @seq, ':=1');
+ERROR HY000: Invalid euckr character string: '\xA2\xE8'
+SET sql_mode=DEFAULT;
+#
+# End of 10.5 tests
+#
diff --git a/mysql-test/main/ctype_euckr.test b/mysql-test/main/ctype_euckr.test
index 46955360217..1154047fdb0 100644
--- a/mysql-test/main/ctype_euckr.test
+++ b/mysql-test/main/ctype_euckr.test
@@ -227,3 +227,20 @@ let $coll_pad='euckr_bin';
 --echo #
 --echo # End of 10.2 tests
 --echo #
+
+
+--echo #
+--echo # Start of 10.5 tests
+--echo #
+
+--echo #
+--echo # MDEV-22625 SIGSEGV in intern_find_sys_var (optimized builds)
+--echo #
+
+SET NAMES euckr;
+SET @seq=_euckr 0xA2E8;
+--source include/ctype_ident_sys.inc
+
+--echo #
+--echo # End of 10.5 tests
+--echo #
diff --git a/mysql-test/main/ctype_gb2312.result b/mysql-test/main/ctype_gb2312.result
index 49db390cee4..d6066f82db9 100644
--- a/mysql-test/main/ctype_gb2312.result
+++ b/mysql-test/main/ctype_gb2312.result
@@ -5079,3 +5079,61 @@ SET DEFAULT_STORAGE_ENGINE=Default;
 #
 # End of 10.2 tests
 #
+#
+# Start of 10.5 tests
+#
+#
+# MDEV-22625 SIGSEGV in intern_find_sys_var (optimized builds)
+#
+SET NAMES gb2312;
+SET @seq=_gb2312 0xA2A1;
+#
+# SET STATEMENT (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT ',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid gb2312 character string: '\xA2\xA1'
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT ',@seq, '.a=1 SELECT 1');
+ERROR HY000: Invalid gb2312 character string: '\xA2\xA1'
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT a.',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid gb2312 character string: '\xA2\xA1'
+#
+# SET SESSION (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET SESSION ',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid gb2312 character string: '\xA2\xA1'
+EXECUTE IMMEDIATE CONCAT('SET SESSION ',@seq, '.a=1 SELECT 1');
+ERROR HY000: Invalid gb2312 character string: '\xA2\xA1'
+EXECUTE IMMEDIATE CONCAT('SET SESSION a.',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid gb2312 character string: '\xA2\xA1'
+#
+# SET (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET ', @seq, '=1');
+ERROR HY000: Invalid gb2312 character string: '\xA2\xA1'
+EXECUTE IMMEDIATE CONCAT('SET ', @seq, '.a=1');
+ERROR HY000: Invalid gb2312 character string: '\xA2\xA1'
+EXECUTE IMMEDIATE CONCAT('SET a.', @seq, '=1');
+ERROR HY000: Invalid gb2312 character string: '\xA2\xA1'
+#
+# Oracle SP call: BEGIN (bad|good.bad|bad.good)(params); END
+#
+SET sql_mode=ORACLE;
+EXECUTE IMMEDIATE CONCAT('BEGIN ',@seq, '(1); END;');
+ERROR HY000: Invalid gb2312 character string: '\xA2\xA1'
+EXECUTE IMMEDIATE CONCAT('BEGIN ',@seq, '.a(1); END;');
+ERROR HY000: Invalid gb2312 character string: '\xA2\xA1'
+EXECUTE IMMEDIATE CONCAT('BEGIN a.',@seq, '(1); END;');
+ERROR HY000: Invalid gb2312 character string: '\xA2\xA1'
+#
+# Oracle assignment: (bad|good.bad|bad.good):= value
+#
+EXECUTE IMMEDIATE CONCAT(@seq, ':=1');
+ERROR HY000: Invalid gb2312 character string: '\xA2\xA1'
+EXECUTE IMMEDIATE CONCAT(@seq, '.a:=1');
+ERROR HY000: Invalid gb2312 character string: '\xA2\xA1'
+EXECUTE IMMEDIATE CONCAT('a.', @seq, ':=1');
+ERROR HY000: Invalid gb2312 character string: '\xA2\xA1'
+SET sql_mode=DEFAULT;
+#
+# End of 10.5 tests
+#
diff --git a/mysql-test/main/ctype_gb2312.test b/mysql-test/main/ctype_gb2312.test
index 4489168a163..07460116ade 100644
--- a/mysql-test/main/ctype_gb2312.test
+++ b/mysql-test/main/ctype_gb2312.test
@@ -180,3 +180,20 @@ let $coll_pad='gb2312_bin';
 --echo #
 --echo # End of 10.2 tests
 --echo #
+
+
+--echo #
+--echo # Start of 10.5 tests
+--echo #
+
+--echo #
+--echo # MDEV-22625 SIGSEGV in intern_find_sys_var (optimized builds)
+--echo #
+
+SET NAMES gb2312;
+SET @seq=_gb2312 0xA2A1;
+--source include/ctype_ident_sys.inc
+
+--echo #
+--echo # End of 10.5 tests
+--echo #
diff --git a/mysql-test/main/ctype_gbk.result b/mysql-test/main/ctype_gbk.result
index fb66631c5cb..7b54794a884 100644
--- a/mysql-test/main/ctype_gbk.result
+++ b/mysql-test/main/ctype_gbk.result
@@ -6542,3 +6542,61 @@ SET DEFAULT_STORAGE_ENGINE=Default;
 #
 # End of 10.2 tests
 #
+#
+# Start of 10.5 tests
+#
+#
+# MDEV-22625 SIGSEGV in intern_find_sys_var (optimized builds)
+#
+SET NAMES gbk;
+SET @seq=_gbk 0xAAA1;
+#
+# SET STATEMENT (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT ',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid gbk character string: '\xAA\xA1'
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT ',@seq, '.a=1 SELECT 1');
+ERROR HY000: Invalid gbk character string: '\xAA\xA1'
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT a.',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid gbk character string: '\xAA\xA1'
+#
+# SET SESSION (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET SESSION ',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid gbk character string: '\xAA\xA1'
+EXECUTE IMMEDIATE CONCAT('SET SESSION ',@seq, '.a=1 SELECT 1');
+ERROR HY000: Invalid gbk character string: '\xAA\xA1'
+EXECUTE IMMEDIATE CONCAT('SET SESSION a.',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid gbk character string: '\xAA\xA1'
+#
+# SET (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET ', @seq, '=1');
+ERROR HY000: Invalid gbk character string: '\xAA\xA1'
+EXECUTE IMMEDIATE CONCAT('SET ', @seq, '.a=1');
+ERROR HY000: Invalid gbk character string: '\xAA\xA1'
+EXECUTE IMMEDIATE CONCAT('SET a.', @seq, '=1');
+ERROR HY000: Invalid gbk character string: '\xAA\xA1'
+#
+# Oracle SP call: BEGIN (bad|good.bad|bad.good)(params); END
+#
+SET sql_mode=ORACLE;
+EXECUTE IMMEDIATE CONCAT('BEGIN ',@seq, '(1); END;');
+ERROR HY000: Invalid gbk character string: '\xAA\xA1'
+EXECUTE IMMEDIATE CONCAT('BEGIN ',@seq, '.a(1); END;');
+ERROR HY000: Invalid gbk character string: '\xAA\xA1'
+EXECUTE IMMEDIATE CONCAT('BEGIN a.',@seq, '(1); END;');
+ERROR HY000: Invalid gbk character string: '\xAA\xA1'
+#
+# Oracle assignment: (bad|good.bad|bad.good):= value
+#
+EXECUTE IMMEDIATE CONCAT(@seq, ':=1');
+ERROR HY000: Invalid gbk character string: '\xAA\xA1'
+EXECUTE IMMEDIATE CONCAT(@seq, '.a:=1');
+ERROR HY000: Invalid gbk character string: '\xAA\xA1'
+EXECUTE IMMEDIATE CONCAT('a.', @seq, ':=1');
+ERROR HY000: Invalid gbk character string: '\xAA\xA1'
+SET sql_mode=DEFAULT;
+#
+# End of 10.5 tests
+#
diff --git a/mysql-test/main/ctype_gbk.test b/mysql-test/main/ctype_gbk.test
index d9d0a4d0ee4..c63c331c643 100644
--- a/mysql-test/main/ctype_gbk.test
+++ b/mysql-test/main/ctype_gbk.test
@@ -484,3 +484,20 @@ let $coll_pad='gbk_bin';
 --echo #
 --echo # End of 10.2 tests
 --echo #
+
+
+--echo #
+--echo # Start of 10.5 tests
+--echo #
+
+--echo #
+--echo # MDEV-22625 SIGSEGV in intern_find_sys_var (optimized builds)
+--echo #
+
+SET NAMES gbk;
+SET @seq=_gbk 0xAAA1;
+--source include/ctype_ident_sys.inc
+
+--echo #
+--echo # End of 10.5 tests
+--echo #
diff --git a/mysql-test/main/ctype_sjis.result b/mysql-test/main/ctype_sjis.result
index fae022b60e1..638f9bc21c7 100644
--- a/mysql-test/main/ctype_sjis.result
+++ b/mysql-test/main/ctype_sjis.result
@@ -19318,3 +19318,61 @@ SET NAMES sjis;
 #
 # End of 10.5 tests
 #
+#
+# Start of 10.5 tests
+#
+#
+# MDEV-22625 SIGSEGV in intern_find_sys_var (optimized builds)
+#
+SET NAMES sjis;
+SET @seq=_sjis 0x81AD;
+#
+# SET STATEMENT (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT ',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid sjis character string: '�_x81�_xAD'
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT ',@seq, '.a=1 SELECT 1');
+ERROR HY000: Invalid sjis character string: '�_x81�_xAD'
+EXECUTE IMMEDIATE CONCAT('SET STATEMENT a.',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid sjis character string: '�_x81�_xAD'
+#
+# SET SESSION (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET SESSION ',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid sjis character string: '�_x81�_xAD'
+EXECUTE IMMEDIATE CONCAT('SET SESSION ',@seq, '.a=1 SELECT 1');
+ERROR HY000: Invalid sjis character string: '�_x81�_xAD'
+EXECUTE IMMEDIATE CONCAT('SET SESSION a.',@seq, '=1 SELECT 1');
+ERROR HY000: Invalid sjis character string: '�_x81�_xAD'
+#
+# SET (bad|good.bad|bad.good)=1
+#
+EXECUTE IMMEDIATE CONCAT('SET ', @seq, '=1');
+ERROR HY000: Invalid sjis character string: '�_x81�_xAD'
+EXECUTE IMMEDIATE CONCAT('SET ', @seq, '.a=1');
+ERROR HY000: Invalid sjis character string: '�_x81�_xAD'
+EXECUTE IMMEDIATE CONCAT('SET a.', @seq, '=1');
+ERROR HY000: Invalid sjis character string: '�_x81�_xAD'
+#
+# Oracle SP call: BEGIN (bad|good.bad|bad.good)(params); END
+#
+SET sql_mode=ORACLE;
+EXECUTE IMMEDIATE CONCAT('BEGIN ',@seq, '(1); END;');
+ERROR HY000: Invalid sjis character string: '�_x81�_xAD'
+EXECUTE IMMEDIATE CONCAT('BEGIN ',@seq, '.a(1); END;');
+ERROR HY000: Invalid sjis character string: '�_x81�_xAD'
+EXECUTE IMMEDIATE CONCAT('BEGIN a.',@seq, '(1); END;');
+ERROR HY000: Invalid sjis character string: '�_x81�_xAD'
+#
+# Oracle assignment: (bad|good.bad|bad.good):= value
+#
+EXECUTE IMMEDIATE CONCAT(@seq, ':=1');
+ERROR HY000: Invalid sjis character string: '�_x81�_xAD'
+EXECUTE IMMEDIATE CONCAT(@seq, '.a:=1');
+ERROR HY000: Invalid sjis character string: '�_x81�_xAD'
+EXECUTE IMMEDIATE CONCAT('a.', @seq, ':=1');
+ERROR HY000: Invalid sjis character string: '�_x81�_xAD'
+SET sql_mode=DEFAULT;
+#
+# End of 10.5 tests
+#
diff --git a/mysql-test/main/ctype_sjis.test b/mysql-test/main/ctype_sjis.test
index 804ba557faa..8ca423bb7c1 100644
--- a/mysql-test/main/ctype_sjis.test
+++ b/mysql-test/main/ctype_sjis.test
@@ -290,3 +290,20 @@ SET NAMES sjis;
 --echo #
 --echo # End of 10.5 tests
 --echo #
+
+
+--echo #
+--echo # Start of 10.5 tests
+--echo #
+
+--echo #
+--echo # MDEV-22625 SIGSEGV in intern_find_sys_var (optimized builds)
+--echo #
+
+SET NAMES sjis;
+SET @seq=_sjis 0x81AD;
+--source include/ctype_ident_sys.inc
+
+--echo #
+--echo # End of 10.5 tests
+--echo #
diff --git a/sql/sql_yacc.yy b/sql/sql_yacc.yy
index 9984448da62..6fe7d871f40 100644
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -16176,13 +16176,15 @@ set_stmt_option:
           ident_cli equal set_expr_or_default
           {
             Lex_ident_sys tmp(thd, &$1);
-            if (unlikely(Lex->set_system_variable(Lex->option_type, &tmp, $3)))
+            if (unlikely(!tmp.str) ||
+                unlikely(Lex->set_system_variable(Lex->option_type, &tmp, $3)))
               MYSQL_YYABORT;
           }
         | ident_cli '.' ident equal set_expr_or_default
           {
             Lex_ident_sys tmp(thd, &$1);
-            if (unlikely(Lex->set_system_variable(thd, Lex->option_type, &tmp, &$3, $5)))
+            if (unlikely(!tmp.str) ||
+                unlikely(Lex->set_system_variable(thd, Lex->option_type, &tmp, &$3, $5)))
               MYSQL_YYABORT;
           }
         | DEFAULT '.' ident equal set_expr_or_default
@@ -16203,7 +16205,8 @@ option_value_following_option_type:
           set_expr_or_default
           {
             Lex_ident_sys tmp(thd, &$1);
-            if (unlikely(Lex->set_system_variable(Lex->option_type, &tmp, $4)) ||
+            if (unlikely(!tmp.str) ||
+                unlikely(Lex->set_system_variable(Lex->option_type, &tmp, $4)) ||
                 unlikely(sp_create_assignment_instr(thd, yychar == YYEMPTY)))
               MYSQL_YYABORT;
           }
@@ -16215,7 +16218,8 @@ option_value_following_option_type:
           set_expr_or_default
           {
             Lex_ident_sys tmp(thd, &$1);
-            if (unlikely(Lex->set_system_variable(thd, Lex->option_type, &tmp, &$3, $6)) ||
+            if (unlikely(!tmp.str) ||
+                unlikely(Lex->set_system_variable(thd, Lex->option_type, &tmp, &$3, $6)) ||
                 unlikely(sp_create_assignment_instr(thd, yychar == YYEMPTY)))
               MYSQL_YYABORT;
           }
@@ -16242,7 +16246,8 @@ option_value_no_option_type:
           set_expr_or_default
           {
             Lex_ident_sys tmp(thd, &$1);
-            if (unlikely(Lex->set_variable(&tmp, $4)) ||
+            if (unlikely(!tmp.str) ||
+                unlikely(Lex->set_variable(&tmp, $4)) ||
                 unlikely(sp_create_assignment_instr(thd, yychar == YYEMPTY)))
               MYSQL_YYABORT;
           }
@@ -16254,7 +16259,8 @@ option_value_no_option_type:
           set_expr_or_default
           {
             Lex_ident_sys tmp(thd, &$1);
-            if (unlikely(Lex->set_variable(&tmp, &$3, $6)) ||
+            if (unlikely(!tmp.str) ||
+                unlikely(Lex->set_variable(&tmp, &$3, $6)) ||
                 unlikely(sp_create_assignment_instr(thd, yychar == YYEMPTY)))
               MYSQL_YYABORT;
           }
@@ -16422,7 +16428,8 @@ option_value_no_option_type:
           set_expr_or_default
           {
             Lex_ident_sys tmp(thd, &$1);
-            if (unlikely(Lex->set_variable(&tmp, $4)) ||
+            if (unlikely(!tmp.str) ||
+                unlikely(Lex->set_variable(&tmp, $4)) ||
                 unlikely(sp_create_assignment_instr(thd, yychar == YYEMPTY)))
               MYSQL_YYABORT;
           }
@@ -18150,14 +18157,16 @@ sp_statement:
           {
             // Direct procedure call (without the CALL keyword)
             Lex_ident_sys tmp(thd, &$1);
-            if (unlikely(Lex->call_statement_start(thd, &tmp)))
+            if (unlikely(!tmp.str) ||
+                unlikely(Lex->call_statement_start(thd, &tmp)))
               MYSQL_YYABORT;
           }
           opt_sp_cparam_list
         | ident_cli_directly_assignable '.' ident
           {
             Lex_ident_sys tmp(thd, &$1);
-            if (unlikely(Lex->call_statement_start(thd, &tmp, &$3)))
+            if (unlikely(!tmp.str) ||
+                unlikely(Lex->call_statement_start(thd, &tmp, &$3)))
               MYSQL_YYABORT;
           }
           opt_sp_cparam_list
@@ -18371,7 +18380,8 @@ set_assign:
           set_expr_or_default
           {
             Lex_ident_sys tmp(thd, &$1);
-            if (unlikely(Lex->set_variable(&tmp, $4)) ||
+            if (unlikely(!tmp.str) ||
+                unlikely(Lex->set_variable(&tmp, $4)) ||
                 unlikely(sp_create_assignment_instr(thd, yychar == YYEMPTY,
                                                     false)))
               MYSQL_YYABORT;
@@ -18388,7 +18398,8 @@ set_assign:
             LEX *lex= Lex;
             DBUG_ASSERT(lex->var_list.is_empty());
             Lex_ident_sys tmp(thd, &$1);
-            if (unlikely(lex->set_variable(&tmp, &$3, $6)) ||
+            if (unlikely(!tmp.str) ||
+                unlikely(lex->set_variable(&tmp, &$3, $6)) ||
                 unlikely(sp_create_assignment_instr(thd, yychar == YYEMPTY,
                                                     false)))
               MYSQL_YYABORT;