This function enables the ability to upload SVG files to the WordPress media library. The code below should be placed within your themes functions.php file. The reason this is disabled by default is because malicious code could be embedded within an SVG file. Please use extreme caution if your site grants users the ability to upload images via the front end.

function upload_svg_files( $allowed ) {
    if ( !current_user_can( 'manage_options' ) )
        return $allowed;
    $allowed['svg'] = 'image/svg+xml';
    return $allowed;
}
add_filter( 'upload_mimes', 'upload_svg_files');