diff --git a/mysql-test/suite/rpl/r/rpl_gtid_header_valid.result b/mysql-test/suite/rpl/r/rpl_gtid_header_valid.result
new file mode 100644
index 00000000000..fd440feb3c9
--- /dev/null
+++ b/mysql-test/suite/rpl/r/rpl_gtid_header_valid.result
@@ -0,0 +1,122 @@
+include/master-slave.inc
+[connection master]
+#
+# Initialize test data
+connection master;
+create table t1 (a int) engine=innodb;
+include/save_master_gtid.inc
+set @@SESSION.debug_dbug= "+d,binlog_force_commit_id";
+connection slave;
+set SQL_LOG_BIN= 0;
+call mtr.add_suppression('Found invalid event in binary log');
+call mtr.add_suppression('Slave SQL.*Relay log read failure: Could not parse relay log event entry.* 1594');
+set SQL_LOG_BIN= 1;
+include/sync_with_master_gtid.inc
+include/stop_slave.inc
+include/start_slave.inc
+#
+# Test FL_PREPARED_XA
+connection master;
+set @@SESSION.debug_dbug= "+d,negate_xid_from_gtid";
+set @commit_id= 100;
+XA START 'x1';
+insert into t1 values (1);
+XA END 'x1';
+XA PREPARE 'x1';
+set @@SESSION.debug_dbug= "-d,negate_xid_from_gtid";
+XA COMMIT 'x1';
+include/save_master_gtid.inc
+# Waiting for slave to find invalid event..
+connection slave;
+include/wait_for_slave_sql_error.inc [errno=1594]
+STOP SLAVE IO_THREAD;
+# Reset master binlogs (as there is an invalid event) and slave state
+connection master;
+RESET MASTER;
+connection slave;
+RESET MASTER;
+RESET SLAVE;
+set @@global.gtid_slave_pos="";
+include/start_slave.inc
+#
+# Test FL_COMPLETED_XA
+connection master;
+set @commit_id= 101;
+XA START 'x1';
+insert into t1 values (2);
+XA END 'x1';
+XA PREPARE 'x1';
+set @@SESSION.debug_dbug= "+d,negate_xid_from_gtid";
+XA COMMIT 'x1';
+set @@SESSION.debug_dbug= "-d,negate_xid_from_gtid";
+include/save_master_gtid.inc
+# Waiting for slave to find invalid event..
+connection slave;
+include/wait_for_slave_sql_error.inc [errno=1594]
+STOP SLAVE IO_THREAD;
+# Cleanup hanging XA PREPARE on slave
+set statement SQL_LOG_BIN=0 for XA COMMIT 'x1';
+# Reset master binlogs (as there is an invalid event) and slave state
+connection master;
+RESET MASTER;
+connection slave;
+RESET MASTER;
+RESET SLAVE;
+set @@global.gtid_slave_pos="";
+include/start_slave.inc
+#
+# Test Missing xid.data (but has format id and length description parts)
+connection master;
+set @commit_id= 101;
+XA START 'x1';
+insert into t1 values (1);
+XA END 'x1';
+XA PREPARE 'x1';
+set @@SESSION.debug_dbug= "+d,negate_xid_data_from_gtid";
+XA COMMIT 'x1';
+set @@SESSION.debug_dbug= "-d,negate_xid_data_from_gtid";
+include/save_master_gtid.inc
+# Waiting for slave to find invalid event..
+connection slave;
+include/wait_for_slave_sql_error.inc [errno=1594]
+STOP SLAVE IO_THREAD;
+# Cleanup hanging XA PREPARE on slave
+set statement SQL_LOG_BIN=0 for XA COMMIT 'x1';
+# Reset master binlogs (as there is an invalid event) and slave state
+connection master;
+RESET MASTER;
+connection slave;
+RESET MASTER;
+RESET SLAVE;
+set @@global.gtid_slave_pos="";
+include/start_slave.inc
+#
+# Test FL_EXTRA_MULTI_ENGINE
+connection master;
+set @old_dbug= @@SESSION.debug_dbug;
+set @@SESSION.debug_dbug= "+d,inject_fl_extra_multi_engine_into_gtid";
+set @commit_id= 102;
+insert into t1 values (3);
+include/save_master_gtid.inc
+set @@SESSION.debug_dbug=@old_dbug;
+connection slave;
+# Waiting for slave to find invalid event..
+include/wait_for_slave_sql_error.inc [errno=1594]
+STOP SLAVE IO_THREAD;
+# Reset master binlogs (as there is an invalid event) and slave state
+connection master;
+RESET MASTER;
+connection slave;
+RESET SLAVE;
+RESET MASTER;
+set @@global.gtid_slave_pos="";
+include/start_slave.inc
+#
+# Cleanup
+connection master;
+drop table t1;
+include/save_master_gtid.inc
+connection slave;
+include/sync_with_master_gtid.inc
+include/rpl_end.inc
+# End of rpl_gtid_header_valid.test
diff --git a/mysql-test/suite/rpl/t/rpl_gtid_header_valid.test b/mysql-test/suite/rpl/t/rpl_gtid_header_valid.test
new file mode 100644
index 00000000000..db546787914
--- /dev/null
+++ b/mysql-test/suite/rpl/t/rpl_gtid_header_valid.test
@@ -0,0 +1,181 @@
+#
+#   This test ensures that, when a GTID event is constructed by reading its
+# content from a binlog file, the reader (e.g. replica, in this test) cannot
+# read beyond the length of the GTID event. That is, we ensure that the
+# structure indicated by its flags and extra_flags are consistent with the
+# actual content of the event.
+#
+#   To spoof a broken GTID log event, we use the DEBUG_DBUG mechanism to inject
+# the master to write invalid GTID events for each flag. The transaction is
+# given a commit id to ensure the event is not shorter than GTID_HEADER_LEN,
+# which would result in zero padding up to GTID_HEADER_LEN.
+#
+#
+# References:
+#   MDEV-33672: Gtid_log_event Construction from File Should Ensure Event
+#               Length When Using Extra Flags
+#
+
+--source include/have_debug.inc
+
+# GTID event extra_flags are format independent
+--source include/have_binlog_format_row.inc
+--source include/have_innodb.inc
+--source include/master-slave.inc
+
+--echo #
+--echo # Initialize test data
+--connection master
+create table t1 (a int) engine=innodb;
+--source include/save_master_gtid.inc
+set @@SESSION.debug_dbug= "+d,binlog_force_commit_id";
+
+--connection slave
+set SQL_LOG_BIN= 0;
+call mtr.add_suppression('Found invalid event in binary log');
+call mtr.add_suppression('Slave SQL.*Relay log read failure: Could not parse relay log event entry.* 1594');
+set SQL_LOG_BIN= 1;
+--source include/sync_with_master_gtid.inc
+--source include/stop_slave.inc
+--source include/start_slave.inc
+--let $cid_ctr= 100
+
+
+--echo #
+--echo # Test FL_PREPARED_XA
+--connection master
+set @@SESSION.debug_dbug= "+d,negate_xid_from_gtid";
+--eval set @commit_id= $cid_ctr
+
+XA START 'x1';
+insert into t1 values (1);
+XA END 'x1';
+XA PREPARE 'x1';
+set @@SESSION.debug_dbug= "-d,negate_xid_from_gtid";
+XA COMMIT 'x1';
+--source include/save_master_gtid.inc
+
+--echo # Waiting for slave to find invalid event..
+--connection slave
+let $slave_sql_errno= 1594; # ER_SLAVE_RELAY_LOG_READ_FAILURE
+source include/wait_for_slave_sql_error.inc;
+STOP SLAVE IO_THREAD;
+
+--echo # Reset master binlogs (as there is an invalid event) and slave state
+--connection master
+RESET MASTER;
+--connection slave
+RESET MASTER;
+RESET SLAVE;
+set @@global.gtid_slave_pos="";
+--source include/start_slave.inc
+
+
+--echo #
+--echo # Test FL_COMPLETED_XA
+--connection master
+--inc $cid_ctr
+--eval set @commit_id= $cid_ctr
+XA START 'x1';
+--let $next_val = `SELECT max(a)+1 FROM t1`
+--eval insert into t1 values ($next_val)
+XA END 'x1';
+XA PREPARE 'x1';
+set @@SESSION.debug_dbug= "+d,negate_xid_from_gtid";
+XA COMMIT 'x1';
+set @@SESSION.debug_dbug= "-d,negate_xid_from_gtid";
+--source include/save_master_gtid.inc
+
+--echo # Waiting for slave to find invalid event..
+--connection slave
+let $slave_sql_errno= 1594; # ER_SLAVE_RELAY_LOG_READ_FAILURE
+source include/wait_for_slave_sql_error.inc;
+STOP SLAVE IO_THREAD;
+
+--echo # Cleanup hanging XA PREPARE on slave
+set statement SQL_LOG_BIN=0 for XA COMMIT 'x1';
+
+--echo # Reset master binlogs (as there is an invalid event) and slave state
+--connection master
+RESET MASTER;
+--connection slave
+RESET MASTER;
+RESET SLAVE;
+set @@global.gtid_slave_pos="";
+--source include/start_slave.inc
+
+
+--echo #
+--echo # Test Missing xid.data (but has format id and length description parts)
+
+--connection master
+--eval set @commit_id= $cid_ctr
+
+XA START 'x1';
+insert into t1 values (1);
+XA END 'x1';
+XA PREPARE 'x1';
+set @@SESSION.debug_dbug= "+d,negate_xid_data_from_gtid";
+XA COMMIT 'x1';
+set @@SESSION.debug_dbug= "-d,negate_xid_data_from_gtid";
+--source include/save_master_gtid.inc
+
+--echo # Waiting for slave to find invalid event..
+--connection slave
+let $slave_sql_errno= 1594; # ER_SLAVE_RELAY_LOG_READ_FAILURE
+source include/wait_for_slave_sql_error.inc;
+STOP SLAVE IO_THREAD;
+
+--echo # Cleanup hanging XA PREPARE on slave
+set statement SQL_LOG_BIN=0 for XA COMMIT 'x1';
+
+--echo # Reset master binlogs (as there is an invalid event) and slave state
+--connection master
+RESET MASTER;
+--connection slave
+RESET MASTER;
+RESET SLAVE;
+set @@global.gtid_slave_pos="";
+--source include/start_slave.inc
+
+
+--echo #
+--echo # Test FL_EXTRA_MULTI_ENGINE
+--connection master
+set @old_dbug= @@SESSION.debug_dbug;
+set @@SESSION.debug_dbug= "+d,inject_fl_extra_multi_engine_into_gtid";
+--inc $cid_ctr
+--eval set @commit_id= $cid_ctr
+--let $next_val = `SELECT max(a)+1 FROM t1`
+--eval insert into t1 values ($next_val)
+--source include/save_master_gtid.inc
+set @@SESSION.debug_dbug=@old_dbug;
+
+--connection slave
+--echo # Waiting for slave to find invalid event..
+let $slave_sql_errno= 1594; # ER_SLAVE_RELAY_LOG_READ_FAILURE
+source include/wait_for_slave_sql_error.inc;
+STOP SLAVE IO_THREAD;
+
+--echo # Reset master binlogs (as there is an invalid event) and slave state
+--connection master
+RESET MASTER;
+
+--connection slave
+RESET SLAVE;
+RESET MASTER;
+set @@global.gtid_slave_pos="";
+--source include/start_slave.inc
+
+--echo #
+--echo # Cleanup
+
+--connection master
+drop table t1;
+--source include/save_master_gtid.inc
+
+--connection slave
+--source include/sync_with_master_gtid.inc
+
+--source include/rpl_end.inc
+--echo # End of rpl_gtid_header_valid.test
diff --git a/sql/log_event.cc b/sql/log_event.cc
index 6779419e682..501dfffb774 100644
--- a/sql/log_event.cc
+++ b/sql/log_event.cc
@@ -2629,6 +2629,11 @@ Gtid_log_event::Gtid_log_event(const uchar *buf, uint event_len,
   }
   if (flags2 & (FL_PREPARED_XA | FL_COMPLETED_XA))
   {
+    if (event_len < static_cast<uint>(buf - buf_0) + 6)
+    {
+      seq_no= 0;
+      return;
+    }
     xid.formatID= uint4korr(buf);
     buf+= 4;
 
@@ -2637,6 +2642,11 @@ Gtid_log_event::Gtid_log_event(const uchar *buf, uint event_len,
     buf+= 2;
 
     long data_length= xid.bqual_length + xid.gtrid_length;
+    if (event_len < static_cast<uint>(buf - buf_0) + data_length)
+    {
+      seq_no= 0;
+      return;
+    }
     memcpy(xid.data, buf, data_length);
     buf+= data_length;
   }
@@ -2651,8 +2661,11 @@ Gtid_log_event::Gtid_log_event(const uchar *buf, uint event_len,
     */
     if (flags_extra & FL_EXTRA_MULTI_ENGINE)
     {
-      DBUG_ASSERT(static_cast<uint>(buf - buf_0) < event_len);
-
+      if (event_len < static_cast<uint>(buf - buf_0) + 1)
+      {
+        seq_no= 0;
+        return;
+      }
       extra_engines= *buf++;
 
       DBUG_ASSERT(extra_engines > 0);
diff --git a/sql/log_event.h b/sql/log_event.h
index fca4015a15d..879a5a78270 100644
--- a/sql/log_event.h
+++ b/sql/log_event.h
@@ -3666,7 +3666,16 @@ public:
   {
     return GTID_HEADER_LEN + ((flags2 & FL_GROUP_COMMIT_ID) ? 2 : 0);
   }
-  bool is_valid() const { return seq_no != 0; }
+
+  bool is_valid() const
+  {
+    /*
+      seq_no is set to 0 if the structure of a serialized GTID event does not
+      align with that as indicated by flags and extra_flags.
+    */
+    return seq_no != 0;
+  }
+
 #ifdef MYSQL_SERVER
   bool write();
   static int make_compatible_event(String *packet, bool *need_dummy_event,
diff --git a/sql/log_event_server.cc b/sql/log_event_server.cc
index 77856cde6f1..f4fddcd1f65 100644
--- a/sql/log_event_server.cc
+++ b/sql/log_event_server.cc
@@ -3411,21 +3411,41 @@ Gtid_log_event::write()
     write_len= GTID_HEADER_LEN + 2;
   }
 
-  if (flags2 & (FL_PREPARED_XA | FL_COMPLETED_XA))
+  if (flags2 & (FL_PREPARED_XA | FL_COMPLETED_XA)
+#ifndef DBUG_OFF
+      && DBUG_EVALUATE_IF("negate_xid_from_gtid", 0, 1)
+#endif
+  )
   {
     int4store(&buf[write_len],   xid.formatID);
     buf[write_len +4]=   (uchar) xid.gtrid_length;
     buf[write_len +4+1]= (uchar) xid.bqual_length;
     write_len+= 6;
     long data_length= xid.bqual_length + xid.gtrid_length;
+
+#ifndef DBUG_OFF
+    if (DBUG_EVALUATE_IF("negate_xid_data_from_gtid", 0, 1))
+    {
+#endif
     memcpy(buf+write_len, xid.data, data_length);
     write_len+= data_length;
+#ifndef DBUG_OFF
+    }
+#endif
   }
+
+  DBUG_EXECUTE_IF("inject_fl_extra_multi_engine_into_gtid", {
+    flags_extra|= FL_EXTRA_MULTI_ENGINE;
+  });
   if (flags_extra > 0)
   {
     buf[write_len]= flags_extra;
     write_len++;
   }
+  DBUG_EXECUTE_IF("inject_fl_extra_multi_engine_into_gtid", {
+    flags_extra&= ~FL_EXTRA_MULTI_ENGINE;
+  });
+
   if (flags_extra & FL_EXTRA_MULTI_ENGINE)
   {
     buf[write_len]= extra_engines;