diff -r 2f6f6f7551ca -r 32102edaa81b web/wp-admin/async-upload.php
--- a/web/wp-admin/async-upload.php	Thu Sep 16 15:45:36 2010 +0000
+++ b/web/wp-admin/async-upload.php	Mon Nov 19 18:26:13 2012 +0100
@@ -21,15 +21,22 @@
 if ( empty($_COOKIE[LOGGED_IN_COOKIE]) && !empty($_REQUEST['logged_in_cookie']) )
 	$_COOKIE[LOGGED_IN_COOKIE] = $_REQUEST['logged_in_cookie'];
 unset($current_user);
-require_once('admin.php');
+require_once('./admin.php');
 
-header('Content-Type: text/plain; charset=' . get_option('blog_charset'));
+header('Content-Type: text/html; charset=' . get_option('blog_charset'));
 
 if ( !current_user_can('upload_files') )
 	wp_die(__('You do not have permission to upload files.'));
 
 // just fetch the detail form for that attachment
 if ( isset($_REQUEST['attachment_id']) && ($id = intval($_REQUEST['attachment_id'])) && $_REQUEST['fetch'] ) {
+	$post = get_post( $id );
+	if ( 'attachment' != $post->post_type )
+		wp_die( __( 'Unknown post type.' ) );
+	$post_type_object = get_post_type_object( 'attachment' );
+	if ( ! current_user_can( $post_type_object->cap->edit_post, $id ) )
+		wp_die( __( 'You are not allowed to edit this item.' ) );
+
 	if ( 2 == $_REQUEST['fetch'] ) {
 		add_filter('attachment_fields_to_edit', 'media_single_attachment_fields_to_edit', 10, 2);
 		echo get_media_item($id, array( 'send' => false, 'delete' => true ));
@@ -43,19 +50,19 @@
 check_admin_referer('media-form');
 
 $id = media_handle_upload('async-upload', $_REQUEST['post_id']);
-if (is_wp_error($id)) {
-	echo '<div id="media-upload-error">'.esc_html($id->get_error_message()).'</div>';
+if ( is_wp_error($id) ) {
+	echo '<div class="error-div">
+	<a class="dismiss" href="#" onclick="jQuery(this).parents(\'div.media-item\').slideUp(200, function(){jQuery(this).remove();});">' . __('Dismiss') . '</a>
+	<strong>' . sprintf(__('&#8220;%s&#8221; has failed to upload due to an error'), esc_html($_FILES['async-upload']['name']) ) . '</strong><br />' .
+	esc_html($id->get_error_message()) . '</div>';
 	exit;
 }
 
 if ( $_REQUEST['short'] ) {
 	// short form response - attachment ID only
 	echo $id;
-}
-else {
+} else {
 	// long form response - big chunk o html
 	$type = $_REQUEST['type'];
 	echo apply_filters("async_upload_{$type}", $id);
 }
-
-?>