diff --git a/mysql-test/suite/sys_vars/r/mdev_32640.result b/mysql-test/suite/sys_vars/r/mdev_32640.result
new file mode 100644
index 00000000000..ea93f3a7c4a
--- /dev/null
+++ b/mysql-test/suite/sys_vars/r/mdev_32640.result
@@ -0,0 +1,15 @@
+PREPARE s_1 FROM 'SHOW RELAYLOG EVENTS';
+/* 1 */ SET default_master_connection='MASTER';
+/* 1 */ EXECUTE s_1;
+ERROR HY000: There is no master connection 'MASTER'
+/* 2 */ SET default_master_connection='MASTER';
+/* 2 */ EXECUTE s_1;
+ERROR HY000: There is no master connection 'MASTER'
+create procedure p() SHOW RELAYLOG EVENTS;
+/* 1 */ SET default_master_connection='MASTER';
+/* 1 */ call p;
+ERROR HY000: There is no master connection 'MASTER'
+/* 2 */ SET default_master_connection='MASTER';
+/* 2 */ call p;
+ERROR HY000: There is no master connection 'MASTER'
+drop procedure p;
diff --git a/mysql-test/suite/sys_vars/t/mdev_32640.test b/mysql-test/suite/sys_vars/t/mdev_32640.test
new file mode 100644
index 00000000000..693bb1e9d16
--- /dev/null
+++ b/mysql-test/suite/sys_vars/t/mdev_32640.test
@@ -0,0 +1,18 @@
+--source include/not_embedded.inc
+
+PREPARE s_1 FROM 'SHOW RELAYLOG EVENTS';
+/* 1 */ SET default_master_connection='MASTER';
+--error WARN_NO_MASTER_INFO
+/* 1 */ EXECUTE s_1;
+/* 2 */ SET default_master_connection='MASTER';
+--error WARN_NO_MASTER_INFO
+/* 2 */ EXECUTE s_1;
+
+create procedure p() SHOW RELAYLOG EVENTS;
+/* 1 */ SET default_master_connection='MASTER';
+--error WARN_NO_MASTER_INFO
+/* 1 */ call p;
+/* 2 */ SET default_master_connection='MASTER';
+--error WARN_NO_MASTER_INFO
+/* 2 */ call p;
+drop procedure p;
diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index db99dfe6d21..2eb27c43081 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -5993,6 +5993,24 @@ finish:
   thd->wsrep_PA_safe= true;
 #endif /* WITH_WSREP */
 
+  /*
+    Reset the connection_name to contain a null string, if the
+    pointer points to the same space as that of the system variable
+    default_master_connection.
+
+    We do this because the system variable may be updated which could
+    free the pointer and create a new one, causing use-after-free for
+    re-execution of prepared statements and stored procedures where
+    the LEX may be reused.
+
+    This allows connection_name to be set again be to the system
+    variable pointer in the next call of this function (see earlier in
+    this function), after any possible updates to the system variable.
+  */
+  if (thd->lex->mi.connection_name.str ==
+      thd->variables.default_master_connection.str)
+    thd->lex->mi.connection_name= null_clex_str;
+
   if (lex->sql_command != SQLCOM_SET_OPTION)
     DEBUG_SYNC(thd, "end_of_statement");
   DBUG_RETURN(res || thd->is_error());