Hardening: Add escaping to the language attributes used on html ele…

…ments.

Merges [42259] to the 4.1 branch.

Built from https://develop.svn.wordpress.org/branches/4.1@42297


git-svn-id: http://core.svn.wordpress.org/branches/4.1@42126 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/general-template.php

@@ -2513,12 +2513,14 @@ function language_attributes($doctype = 'html') {
 	if ( function_exists( 'is_rtl' ) && is_rtl() )
 		$attributes[] = 'dir="rtl"';
 
-	if ( $lang = get_bloginfo('language') ) {
-		if ( get_option('html_type') == 'text/html' || $doctype == 'html' )
-			$attributes[] = "lang=\"$lang\"";
+	if ( $lang = get_bloginfo( 'language' ) ) {
+		if ( get_option( 'html_type' ) == 'text/html' || $doctype == 'html' ) {
+			$attributes[] = 'lang="' . esc_attr( $lang ) . '"';
+		}
 
-		if ( get_option('html_type') != 'text/html' || $doctype == 'xhtml' )
-			$attributes[] = "xml:lang=\"$lang\"";
+		if ( get_option( 'html_type' ) != 'text/html' || $doctype == 'xhtml' ) {
+			$attributes[] = 'xml:lang="' . esc_attr( $lang ) . '"';
+		}
 	}
 
 	$output = implode(' ', $attributes);