Index: wp-admin/includes/file.php
===================================================================
--- wp-admin/includes/file.php	(revision 43051)
+++ wp-admin/includes/file.php	(working copy)
@@ -2042,7 +2042,7 @@
 	$obscura              = wp_generate_password( 32, false, false );
 	$file_basename        = 'wp-personal-data-file-' . $stripped_email . '-' . $obscura;
 	$html_report_filename = $file_basename . '.html';
-	$html_report_pathname = $exports_dir . $html_report_filename;
+	$html_report_pathname = wp_normalize_path( $exports_dir . $html_report_filename );
 	$file = fopen( $html_report_pathname, 'w' );
 	if ( false === $file ) {
 		wp_send_json_error( __( 'Unable to open export file (HTML report) for writing' ) );
@@ -2160,7 +2160,7 @@
 
 	// Save the export file in the request.
 	update_post_meta( $request_id, '_export_file_url', $archive_url );
-	update_post_meta( $request_id, '_export_file_path', $archive_pathname );
+	update_post_meta( $request_id, '_export_file_path', wp_normalize_path( $archive_pathname ) );
 }
 
 /**