Ticket #33591: 33591.5.diff

src/wp-includes/feed.php

@@ -502 +502 @@
         foreach ( (array) get_post_custom() as $key => $val ) {
                 if ($key == 'enclosure') {
                         foreach ( (array) $val as $enc ) {
-                                $enclosure = explode("\n", $enc);
+
+                                /* Since enclosures are passed-in line-delimited,
+                                 * the best we can do is attempt to validate the values
+                                 * before rendering them.
+                                */
+                                $enclosure = explode( "\n", $enc );
+
+                                $url = '';
+                                $legth = '';
+                                $type = '';
+
+                                if ( isset( $enclosure[0] ) && is_string( $enclosure[0] ) ) {
+                                        $url = $enclosure[0];
+                                }
+
+                                if ( isset( $enclosure[1] && is_numeric( $enclosure[1] ) ) {
+                                        $length = $enclosure[1];
+                                }
+
+                                if ( isset( $enclosure[2] && in_array( $enclosure[2], get_allowed_mime_types() ) ) {
+                                        $type = $enclosure[2];
+                                }
+
+                                $html_link_tag = '<link href="' . esc_url ( $url ) . '" rel="enclosure" length="' . esc_attr( $length ) . '" type="' . esc_attr( $type ) . '" />' . "\n";
+
                                 /**
                                  * Filters the atom enclosure HTML link tag for the current post.
                                  *
@@ -510 +534 @@
                                  *
                                  * @param string $html_link_tag The HTML link tag with a URI and other attributes.
                                  */
-                                echo apply_filters( 'atom_enclosure', '<link href="' . trim( htmlspecialchars( $enclosure[0] ) ) . '" rel="enclosure" length="' . trim( $enclosure[1] ) . '" type="' . trim( $enclosure[2] ) . '" />' . "\n" );
+                                echo apply_filters( 'atom_enclosure', $html_link_tag );
                         }
                 }
         }