diff --git a/plugins/mysqlx/include/mysqlx_session.h b/plugins/mysqlx/include/mysqlx_session.h
index 9f23c1728..da551adc9 100644
--- a/plugins/mysqlx/include/mysqlx_session.h
+++ b/plugins/mysqlx/include/mysqlx_session.h
@@ -25,12 +25,30 @@ typedef struct ZSTD_CCtx_s ZSTD_CCtx;
 using MysqlxIdentityLookup =
 	std::function<std::optional<MysqlxResolvedIdentity>(const std::string& username)>;
 
+// Per-message response state for the X-Protocol response sequence the
+// proxy is currently waiting on. The X protocol defines distinct frame
+// allow-sets and terminal markers per request type; this enum splits
+// PREPARE and CURSOR into their per-request sub-shapes so each per-state
+// contract can be expressed cleanly in is_frame_allowed / is_terminal_frame.
+//
+// Background: the previous coarse three-value model (PREPARE / CURSOR
+// each lumped together) over-accepted on PREPARE_PREPARE — which the
+// spec terminates with a bare Mysqlx.Ok — by also allowing the wider
+// SQL_STMT_EXECUTE_OK / FETCH_DONE_* terminators that only PREPARE_EXECUTE
+// can legitimately emit. Likewise CURSOR_OPEN's response always carries
+// ColumnMetaData while CURSOR_FETCH's never does (the metadata is sent
+// once at Open). Splitting the state lets the validation hook reject
+// out-of-shape backend frames precisely.
 enum MysqlxResponseState {
 	RESP_IDLE = 0,
 	RESP_WAITING_STMT_EXECUTE,
 	RESP_WAITING_CRUD,
-	RESP_WAITING_PREPARE,
-	RESP_WAITING_CURSOR,
+	RESP_WAITING_PREPARE_PREPARE,        // Prepare::Prepare — terminator: Ok
+	RESP_WAITING_PREPARE_EXECUTE,        // Prepare::Execute — terminators: Ok / SQL_STMT_EXECUTE_OK / FETCH_DONE / FETCH_SUSPENDED
+	RESP_WAITING_PREPARE_DEALLOCATE,     // Prepare::Deallocate — terminator: Ok
+	RESP_WAITING_CURSOR_OPEN,            // Cursor::Open — terminators: FETCH_DONE / FETCH_SUSPENDED; carries ColumnMetaData
+	RESP_WAITING_CURSOR_FETCH,           // Cursor::Fetch — terminators: FETCH_DONE / FETCH_SUSPENDED; rows-only (metadata was at Open)
+	RESP_WAITING_CURSOR_CLOSE,           // Cursor::Close — terminator: Ok
 	RESP_WAITING_EXPECT,
 	RESP_WAITING_SESS_RESET
 };
diff --git a/plugins/mysqlx/src/mysqlx_session.cpp b/plugins/mysqlx/src/mysqlx_session.cpp
index 42e969ef3..374fc4034 100644
--- a/plugins/mysqlx/src/mysqlx_session.cpp
+++ b/plugins/mysqlx/src/mysqlx_session.cpp
@@ -839,16 +839,22 @@ int MysqlxSession::dispatch_client_message(uint8_t msg_type) {
 			forward_to_backend(); return 0;
 		case Mysqlx::ClientMessages_Type_PREPARE_PREPARE:
 			if (backend_conn_) backend_conn_->set_has_prepared_statement(true);
-			response_state_ = RESP_WAITING_PREPARE;
+			response_state_ = RESP_WAITING_PREPARE_PREPARE;
 			forward_to_backend(); return 0;
 		case Mysqlx::ClientMessages_Type_PREPARE_EXECUTE:
+			response_state_ = RESP_WAITING_PREPARE_EXECUTE;
+			forward_to_backend(); return 0;
 		case Mysqlx::ClientMessages_Type_PREPARE_DEALLOCATE:
-			response_state_ = RESP_WAITING_PREPARE;
+			response_state_ = RESP_WAITING_PREPARE_DEALLOCATE;
 			forward_to_backend(); return 0;
 		case Mysqlx::ClientMessages_Type_CURSOR_OPEN:
+			response_state_ = RESP_WAITING_CURSOR_OPEN;
+			forward_to_backend(); return 0;
 		case Mysqlx::ClientMessages_Type_CURSOR_FETCH:
+			response_state_ = RESP_WAITING_CURSOR_FETCH;
+			forward_to_backend(); return 0;
 		case Mysqlx::ClientMessages_Type_CURSOR_CLOSE:
-			response_state_ = RESP_WAITING_CURSOR;
+			response_state_ = RESP_WAITING_CURSOR_CLOSE;
 			forward_to_backend(); return 0;
 		case Mysqlx::ClientMessages_Type_EXPECT_OPEN:
 		case Mysqlx::ClientMessages_Type_EXPECT_CLOSE:
@@ -950,11 +956,31 @@ bool MysqlxSession::is_terminal_frame(uint8_t msg_type) const {
 			return msg_type == Mysqlx::ServerMessages_Type_OK ||
 			       msg_type == Mysqlx::ServerMessages_Type_RESULTSET_FETCH_DONE ||
 			       msg_type == Mysqlx::ServerMessages_Type_RESULTSET_FETCH_SUSPENDED;
-		case RESP_WAITING_PREPARE:
+		case RESP_WAITING_PREPARE_PREPARE:
+			// Prepare::Prepare returns only Mysqlx.Ok on success.
+			return msg_type == Mysqlx::ServerMessages_Type_OK;
+		case RESP_WAITING_PREPARE_EXECUTE:
+			// Prepare::Execute behaves like the underlying request — for
+			// statement preparations the terminator is SQL_STMT_EXECUTE_OK,
+			// for CRUD it's Ok, for cursor-bound preparations it's
+			// FETCH_DONE / FETCH_SUSPENDED. Accept all four; the proxy
+			// can't tell at this layer which kind was prepared.
+			return msg_type == Mysqlx::ServerMessages_Type_OK ||
+			       msg_type == Mysqlx::ServerMessages_Type_SQL_STMT_EXECUTE_OK ||
+			       msg_type == Mysqlx::ServerMessages_Type_RESULTSET_FETCH_DONE ||
+			       msg_type == Mysqlx::ServerMessages_Type_RESULTSET_FETCH_SUSPENDED;
+		case RESP_WAITING_PREPARE_DEALLOCATE:
+			// Prepare::Deallocate returns only Mysqlx.Ok.
 			return msg_type == Mysqlx::ServerMessages_Type_OK;
-		case RESP_WAITING_CURSOR:
+		case RESP_WAITING_CURSOR_OPEN:
 			return msg_type == Mysqlx::ServerMessages_Type_RESULTSET_FETCH_DONE ||
 			       msg_type == Mysqlx::ServerMessages_Type_RESULTSET_FETCH_SUSPENDED;
+		case RESP_WAITING_CURSOR_FETCH:
+			return msg_type == Mysqlx::ServerMessages_Type_RESULTSET_FETCH_DONE ||
+			       msg_type == Mysqlx::ServerMessages_Type_RESULTSET_FETCH_SUSPENDED;
+		case RESP_WAITING_CURSOR_CLOSE:
+			// Cursor::Close returns only Mysqlx.Ok.
+			return msg_type == Mysqlx::ServerMessages_Type_OK;
 		case RESP_WAITING_EXPECT:
 			return msg_type == Mysqlx::ServerMessages_Type_OK;
 		case RESP_WAITING_SESS_RESET: