- return apply_filters( 'wp_get_attachment_link', "<a href='$url'>$link_text</a>", $id, $size, $permalink, $icon, $text );
+ return apply_filters( 'wp_get_attachment_link', "<a href='" . esc_url( $url ) . "'>$link_text</a>", $id, $size, $permalink, $icon, $text );