Ticket #24824: 24824.diff

src/wp-includes/post.php

@@ -289 +289 @@
         $file = get_post_meta( $attachment_id, '_wp_attached_file', true );
 
         // If the file is relative, prepend upload dir.
-        if ( $file && 0 !== strpos( $file, '/' ) && ! preg_match( '|^.:\\\|', $file ) && ( ( $uploads = wp_get_upload_dir() ) && false === $uploads['error'] ) ) {
-                $file = $uploads['basedir'] . "/$file";
+        if ( ( $uploads = wp_get_upload_dir() ) && ! preg_match('|://|', $file) && false === $uploads['error'] ) {
+                $file = path_join($uploads['basedir'], $file);
         }
 
         if ( $unfiltered ) {