diff --git a/wp-includes/class-wp-xmlrpc-server.php b/wp-includes/class-wp-xmlrpc-server.php
index 53566cbeff..945d659fb0 100644
--- a/wp-includes/class-wp-xmlrpc-server.php
+++ b/wp-includes/class-wp-xmlrpc-server.php
@@ -4311,7 +4311,7 @@ class wp_xmlrpc_server extends IXR_Server {
 		do_action( 'xmlrpc_call', 'wp.getMediaItem' );
 
 		$attachment = get_post( $attachment_id );
-		if ( ! $attachment ) {
+		if ( ! $attachment || 'attachment' !== $attachment->post_type ) {
 			return new IXR_Error( 404, __( 'Invalid attachment ID.' ) );
 		}
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 24de64015e..0569a16ea2 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.6-beta2-49384';
+$wp_version = '5.6-beta2-49385';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.