Grouped backports to the 4.3 branch.

- Media: Prevent CSRF setting attachment thumbnails.

Merges [55764] to the 4.3 branch.
Props dd32, isabel_brison, martinkrcho, matveb, ocean90, paulkevan, peterwilsoncc, timothyblynjacobs, xknown, youknowriad.

git-svn-id: https://develop.svn.wordpress.org/branches/4.3@55776 602fd350-edb4-49c9-b593-d223f7449a82

package-lock.json

@@ -1,6 +1,6 @@
 {
 	"name": "WordPress",
-	"version": "4.3.30",
+	"version": "4.3.31",
 	"lockfileVersion": 1,
 	"requires": true,
 	"dependencies": {

package.json

@@ -1,6 +1,6 @@
 {
 	"name": "WordPress",
-	"version": "4.3.30",
+	"version": "4.3.31",
 	"description": "WordPress is web software you can use to create a beautiful website or blog.",
 	"repository": {
 		"type": "svn",

src/wp-admin/about.php

@@ -108,7 +108,27 @@ $tech_features = array(
 		</h2>
 
 		<div class="changelog point-releases">
-			<h3><?php echo _n( 'Maintenance and Security Release', 'Maintenance and Security Releases', 30 ); ?></h3>
+			<h3><?php echo _n( 'Maintenance and Security Release', 'Maintenance and Security Releases', 31 ); ?></h3>
+			<p>
+				<?php
+				printf(
+					/* translators: %s: WordPress version number */
+					__( '<strong>Version %s</strong> addressed one security issue.' ),
+					'4.3.31'
+				);
+				?>
+				<?php
+				printf(
+					/* translators: %s: HelpHub URL */
+					__( 'For more information, see <a href="%s">the release notes</a>.' ),
+					sprintf(
+						/* translators: %s: WordPress version */
+						esc_url( __( 'https://wordpress.org/support/wordpress-version/version-%s/' ) ),
+						sanitize_title( '4.3.31' )
+					)
+				);
+				?>
+			</p>
 			<p>
 				<?php
 				printf(

src/wp-admin/includes/ajax-actions.php

@@ -2059,6 +2059,10 @@ function wp_ajax_set_attachment_thumbnail() {
 		wp_send_json_error();
 	}
 
+	if ( false === check_ajax_referer( 'set-attachment-thumbnail', '_ajax_nonce', false ) ) {
+		wp_send_json_error();
+	}
+
 	$post_ids = array();
 	// For each URL, try to find its corresponding post ID.
 	foreach ( $_POST['urls'] as $url ) {

src/wp-includes/js/media/views/frame/video-details.js

@@ -104,6 +104,7 @@ VideoDetails = MediaDetails.extend({
 
 			wp.ajax.send( 'set-attachment-thumbnail', {
 				data : {
+					_ajax_nonce: wp.media.view.settings.nonce.setAttachmentThumbnail,
 					urls: urls,
 					thumbnail_id: attachment.get( 'id' )
 				}

src/wp-includes/media.php

@@ -2977,7 +2977,8 @@ function wp_enqueue_media( $args = array() ) {
 		/** This filter is documented in wp-admin/includes/media.php */
 		'captions'  => ! apply_filters( 'disable_captions', '' ),
 		'nonce'     => array(
-			'sendToEditor' => wp_create_nonce( 'media-send-to-editor' ),
+			'sendToEditor'           => wp_create_nonce( 'media-send-to-editor' ),
+			'setAttachmentThumbnail' => wp_create_nonce( 'set-attachment-thumbnail' ),
 		),
 		'post'    => array(
 			'id' => 0,

src/wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.3.30-src';
+$wp_version = '4.3.31-src';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.