diff -r 3d4e9c994f10 -r a86126ab1dd4 wp/wp-includes/widgets/class-wp-widget-recent-posts.php
--- a/wp/wp-includes/widgets/class-wp-widget-recent-posts.php	Tue Oct 22 16:11:46 2019 +0200
+++ b/wp/wp-includes/widgets/class-wp-widget-recent-posts.php	Tue Dec 15 13:49:49 2020 +0100
@@ -45,7 +45,8 @@
 			$args['widget_id'] = $this->id;
 		}
 
-		$title = ( ! empty( $instance['title'] ) ) ? $instance['title'] : __( 'Recent Posts' );
+		$default_title = __( 'Recent Posts' );
+		$title         = ( ! empty( $instance['title'] ) ) ? $instance['title'] : $default_title;
 
 		/** This filter is documented in wp-includes/widgets/class-wp-widget-pages.php */
 		$title = apply_filters( 'widget_title', $title, $instance, $this->id_base );
@@ -56,18 +57,18 @@
 		}
 		$show_date = isset( $instance['show_date'] ) ? $instance['show_date'] : false;
 
-		/**
-		 * Filters the arguments for the Recent Posts widget.
-		 *
-		 * @since 3.4.0
-		 * @since 4.9.0 Added the `$instance` parameter.
-		 *
-		 * @see WP_Query::get_posts()
-		 *
-		 * @param array $args     An array of arguments used to retrieve the recent posts.
-		 * @param array $instance Array of settings for the current widget.
-		 */
 		$r = new WP_Query(
+			/**
+			 * Filters the arguments for the Recent Posts widget.
+			 *
+			 * @since 3.4.0
+			 * @since 4.9.0 Added the `$instance` parameter.
+			 *
+			 * @see WP_Query::get_posts()
+			 *
+			 * @param array $args     An array of arguments used to retrieve the recent posts.
+			 * @param array $instance Array of settings for the current widget.
+			 */
 			apply_filters(
 				'widget_posts_args',
 				array(
@@ -84,27 +85,52 @@
 			return;
 		}
 		?>
+
 		<?php echo $args['before_widget']; ?>
+
 		<?php
 		if ( $title ) {
 			echo $args['before_title'] . $title . $args['after_title'];
 		}
+
+		$format = current_theme_supports( 'html5', 'navigation-widgets' ) ? 'html5' : 'xhtml';
+
+		/** This filter is documented in wp-includes/widgets/class-wp-nav-menu-widget.php */
+		$format = apply_filters( 'navigation_widgets_format', $format );
+
+		if ( 'html5' === $format ) {
+			// The title may be filtered: Strip out HTML and make sure the aria-label is never empty.
+			$title      = trim( strip_tags( $title ) );
+			$aria_label = $title ? $title : $default_title;
+			echo '<nav role="navigation" aria-label="' . esc_attr( $aria_label ) . '">';
+		}
 		?>
+
 		<ul>
 			<?php foreach ( $r->posts as $recent_post ) : ?>
 				<?php
-				$post_title = get_the_title( $recent_post->ID );
-				$title      = ( ! empty( $post_title ) ) ? $post_title : __( '(no title)' );
+				$post_title   = get_the_title( $recent_post->ID );
+				$title        = ( ! empty( $post_title ) ) ? $post_title : __( '(no title)' );
+				$aria_current = '';
+
+				if ( get_queried_object_id() === $recent_post->ID ) {
+					$aria_current = ' aria-current="page"';
+				}
 				?>
 				<li>
-					<a href="<?php the_permalink( $recent_post->ID ); ?>"><?php echo $title; ?></a>
+					<a href="<?php the_permalink( $recent_post->ID ); ?>"<?php echo $aria_current; ?>><?php echo $title; ?></a>
 					<?php if ( $show_date ) : ?>
 						<span class="post-date"><?php echo get_the_date( '', $recent_post->ID ); ?></span>
 					<?php endif; ?>
 				</li>
 			<?php endforeach; ?>
 		</ul>
+
 		<?php
+		if ( 'html5' === $format ) {
+			echo '</nav>';
+		}
+
 		echo $args['after_widget'];
 	}
 
@@ -138,14 +164,20 @@
 		$number    = isset( $instance['number'] ) ? absint( $instance['number'] ) : 5;
 		$show_date = isset( $instance['show_date'] ) ? (bool) $instance['show_date'] : false;
 		?>
-		<p><label for="<?php echo $this->get_field_id( 'title' ); ?>"><?php _e( 'Title:' ); ?></label>
-		<input class="widefat" id="<?php echo $this->get_field_id( 'title' ); ?>" name="<?php echo $this->get_field_name( 'title' ); ?>" type="text" value="<?php echo $title; ?>" /></p>
+		<p>
+			<label for="<?php echo $this->get_field_id( 'title' ); ?>"><?php _e( 'Title:' ); ?></label>
+			<input class="widefat" id="<?php echo $this->get_field_id( 'title' ); ?>" name="<?php echo $this->get_field_name( 'title' ); ?>" type="text" value="<?php echo $title; ?>" />
+		</p>
 
-		<p><label for="<?php echo $this->get_field_id( 'number' ); ?>"><?php _e( 'Number of posts to show:' ); ?></label>
-		<input class="tiny-text" id="<?php echo $this->get_field_id( 'number' ); ?>" name="<?php echo $this->get_field_name( 'number' ); ?>" type="number" step="1" min="1" value="<?php echo $number; ?>" size="3" /></p>
+		<p>
+			<label for="<?php echo $this->get_field_id( 'number' ); ?>"><?php _e( 'Number of posts to show:' ); ?></label>
+			<input class="tiny-text" id="<?php echo $this->get_field_id( 'number' ); ?>" name="<?php echo $this->get_field_name( 'number' ); ?>" type="number" step="1" min="1" value="<?php echo $number; ?>" size="3" />
+		</p>
 
-		<p><input class="checkbox" type="checkbox"<?php checked( $show_date ); ?> id="<?php echo $this->get_field_id( 'show_date' ); ?>" name="<?php echo $this->get_field_name( 'show_date' ); ?>" />
-		<label for="<?php echo $this->get_field_id( 'show_date' ); ?>"><?php _e( 'Display post date?' ); ?></label></p>
+		<p>
+			<input class="checkbox" type="checkbox"<?php checked( $show_date ); ?> id="<?php echo $this->get_field_id( 'show_date' ); ?>" name="<?php echo $this->get_field_name( 'show_date' ); ?>" />
+			<label for="<?php echo $this->get_field_id( 'show_date' ); ?>"><?php _e( 'Display post date?' ); ?></label>
+		</p>
 		<?php
 	}
 }