diff --git a/wp-admin/includes/class-walker-category-checklist.php b/wp-admin/includes/class-walker-category-checklist.php
index 3647d8770b..f4d3fbed36 100644
--- a/wp-admin/includes/class-walker-category-checklist.php
+++ b/wp-admin/includes/class-walker-category-checklist.php
@@ -83,7 +83,7 @@ class Walker_Category_Checklist extends Walker {
 
 		$args['popular_cats'] = empty( $args['popular_cats'] ) ? array() : $args['popular_cats'];
 
-		$class = in_array( $category->term_id, $args['popular_cats'] ) ? ' class="popular-category"' : '';
+		$class = in_array( $category->term_id, $args['popular_cats'], true ) ? ' class="popular-category"' : '';
 
 		$args['selected_cats'] = empty( $args['selected_cats'] ) ? array() : $args['selected_cats'];
 
@@ -91,7 +91,7 @@ class Walker_Category_Checklist extends Walker {
 			$aria_checked = 'false';
 			$inner_class  = 'category';
 
-			if ( in_array( $category->term_id, $args['selected_cats'] ) ) {
+			if ( in_array( $category->term_id, $args['selected_cats'], true ) ) {
 				$inner_class .= ' selected';
 				$aria_checked = 'true';
 			}
@@ -102,10 +102,13 @@ class Walker_Category_Checklist extends Walker {
 				/** This filter is documented in wp-includes/category-template.php */
 				esc_html( apply_filters( 'the_category', $category->name, '', '' ) ) . '</div>';
 		} else {
+			$is_selected = in_array( $category->term_id, $args['selected_cats'], true );
+			$is_disabled = ! empty( $args['disabled'] );
+
 			$output .= "\n<li id='{$taxonomy}-{$category->term_id}'$class>" .
 				'<label class="selectit"><input value="' . $category->term_id . '" type="checkbox" name="' . $name . '[]" id="in-' . $taxonomy . '-' . $category->term_id . '"' .
-				checked( in_array( $category->term_id, $args['selected_cats'] ), true, false ) .
-				disabled( empty( $args['disabled'] ), false, false ) . ' /> ' .
+				checked( $is_selected, true, false ) .
+				disabled( $is_disabled, true, false ) . ' /> ' .
 				/** This filter is documented in wp-includes/category-template.php */
 				esc_html( apply_filters( 'the_category', $category->name, '', '' ) ) . '</label>';
 		}
diff --git a/wp-admin/includes/class-wp-filesystem-base.php b/wp-admin/includes/class-wp-filesystem-base.php
index d9459b31df..fe96929b5c 100644
--- a/wp-admin/includes/class-wp-filesystem-base.php
+++ b/wp-admin/includes/class-wp-filesystem-base.php
@@ -401,7 +401,7 @@ class WP_Filesystem_Base {
 		$attarray = preg_split( '//', $mode );
 
 		for ( $i = 0, $c = count( $attarray ); $i < $c; $i++ ) {
-			$key = array_search( $attarray[ $i ], $legal );
+			$key = array_search( $attarray[ $i ], $legal, true );
 			if ( $key ) {
 				$realmode .= $legal[ $key ];
 			}
diff --git a/wp-admin/includes/class-wp-ms-users-list-table.php b/wp-admin/includes/class-wp-ms-users-list-table.php
index 4f2932acdc..57968ae935 100644
--- a/wp-admin/includes/class-wp-ms-users-list-table.php
+++ b/wp-admin/includes/class-wp-ms-users-list-table.php
@@ -505,7 +505,7 @@ class WP_MS_Users_List_Table extends WP_List_Table {
 			$actions['edit'] = '<a href="' . $edit_link . '">' . __( 'Edit' ) . '</a>';
 		}
 
-		if ( current_user_can( 'delete_user', $user->ID ) && ! in_array( $user->user_login, $super_admins ) ) {
+		if ( current_user_can( 'delete_user', $user->ID ) && ! in_array( $user->user_login, $super_admins, true ) ) {
 			$actions['delete'] = '<a href="' . esc_url( network_admin_url( add_query_arg( '_wp_http_referer', urlencode( wp_unslash( $_SERVER['REQUEST_URI'] ) ), wp_nonce_url( 'users.php', 'deleteuser' ) . '&amp;action=deleteuser&amp;id=' . $user->ID ) ) ) . '" class="delete">' . __( 'Delete' ) . '</a>';
 		}
 
diff --git a/wp-admin/includes/class-wp-terms-list-table.php b/wp-admin/includes/class-wp-terms-list-table.php
index 03b997a443..2d9aca5932 100644
--- a/wp-admin/includes/class-wp-terms-list-table.php
+++ b/wp-admin/includes/class-wp-terms-list-table.php
@@ -300,7 +300,7 @@ class WP_Terms_List_Table extends WP_List_Table {
 					$my_parent    = get_term( $p, $taxonomy );
 					$my_parents[] = $my_parent;
 					$p            = $my_parent->parent;
-					if ( in_array( $p, $parent_ids ) ) { // Prevent parent loops.
+					if ( in_array( $p, $parent_ids, true ) ) { // Prevent parent loops.
 						break;
 					}
 					$parent_ids[] = $p;
diff --git a/wp-admin/includes/dashboard.php b/wp-admin/includes/dashboard.php
index 2a31c6c0b3..11fb18268c 100644
--- a/wp-admin/includes/dashboard.php
+++ b/wp-admin/includes/dashboard.php
@@ -519,7 +519,7 @@ function wp_dashboard_quick_press( $error_msg = false ) {
 		$post    = get_default_post_to_edit( 'post', true );
 		$user_id = get_current_user_id();
 		// Don't create an option if this is a super admin who does not belong to this site.
-		if ( in_array( get_current_blog_id(), array_keys( get_blogs_of_user( $user_id ) ) ) ) {
+		if ( in_array( get_current_blog_id(), array_keys( get_blogs_of_user( $user_id ) ), true ) ) {
 			update_user_option( $user_id, 'dashboard_quick_press_last_post_id', (int) $post->ID ); // Save post_ID.
 		}
 	}
diff --git a/wp-admin/includes/ms.php b/wp-admin/includes/ms.php
index f1567cb5d4..f683c737ef 100644
--- a/wp-admin/includes/ms.php
+++ b/wp-admin/includes/ms.php
@@ -922,19 +922,23 @@ function confirm_delete_users( $users ) {
 							'fields'  => array( 'ID', 'user_login' ),
 						)
 					);
+
 					if ( is_array( $blog_users ) && ! empty( $blog_users ) ) {
 						$user_site      = "<a href='" . esc_url( get_home_url( $details->userblog_id ) ) . "'>{$details->blogname}</a>";
 						$user_dropdown  = '<label for="reassign_user" class="screen-reader-text">' . __( 'Select a user' ) . '</label>';
 						$user_dropdown .= "<select name='blog[$user_id][$key]' id='reassign_user'>";
 						$user_list      = '';
+
 						foreach ( $blog_users as $user ) {
-							if ( ! in_array( $user->ID, $allusers ) ) {
+							if ( ! in_array( (int) $user->ID, $allusers, true ) ) {
 								$user_list .= "<option value='{$user->ID}'>{$user->user_login}</option>";
 							}
 						}
+
 						if ( '' == $user_list ) {
 							$user_list = $admin_out;
 						}
+
 						$user_dropdown .= $user_list;
 						$user_dropdown .= "</select>\n";
 						?>
diff --git a/wp-admin/includes/nav-menu.php b/wp-admin/includes/nav-menu.php
index e3d1053f77..64dda1db61 100644
--- a/wp-admin/includes/nav-menu.php
+++ b/wp-admin/includes/nav-menu.php
@@ -1149,8 +1149,10 @@ function wp_nav_menu_update_menu_items( $nav_menu_selected_id, $nav_menu_selecte
 			'post_status' => 'draft,publish',
 		)
 	);
-	$messages            = array();
-	$menu_items          = array();
+
+	$messages   = array();
+	$menu_items = array();
+
 	// Index menu items by DB ID.
 	foreach ( $unsorted_menu_items as $_item ) {
 		$menu_items[ $_item->db_id ] = $_item;
@@ -1173,6 +1175,7 @@ function wp_nav_menu_update_menu_items( $nav_menu_selected_id, $nav_menu_selecte
 	);
 
 	wp_defer_term_counting( true );
+
 	// Loop through all the menu items' POST variables.
 	if ( ! empty( $_POST['menu-item-db-id'] ) ) {
 		foreach ( (array) $_POST['menu-item-db-id'] as $_key => $k ) {
@@ -1209,19 +1212,22 @@ function wp_nav_menu_update_menu_items( $nav_menu_selected_id, $nav_menu_selecte
 	// Store 'auto-add' pages.
 	$auto_add        = ! empty( $_POST['auto-add-pages'] );
 	$nav_menu_option = (array) get_option( 'nav_menu_options' );
+
 	if ( ! isset( $nav_menu_option['auto_add'] ) ) {
 		$nav_menu_option['auto_add'] = array();
 	}
+
 	if ( $auto_add ) {
-		if ( ! in_array( $nav_menu_selected_id, $nav_menu_option['auto_add'] ) ) {
+		if ( ! in_array( $nav_menu_selected_id, $nav_menu_option['auto_add'], true ) ) {
 			$nav_menu_option['auto_add'][] = $nav_menu_selected_id;
 		}
 	} else {
-		$key = array_search( $nav_menu_selected_id, $nav_menu_option['auto_add'] );
+		$key = array_search( $nav_menu_selected_id, $nav_menu_option['auto_add'], true );
 		if ( false !== $key ) {
 			unset( $nav_menu_option['auto_add'][ $key ] );
 		}
 	}
+
 	// Remove non-existent/deleted menus.
 	$nav_menu_option['auto_add'] = array_intersect( $nav_menu_option['auto_add'], wp_get_nav_menus( array( 'fields' => 'ids' ) ) );
 	update_option( 'nav_menu_options', $nav_menu_option );
diff --git a/wp-admin/includes/plugin.php b/wp-admin/includes/plugin.php
index 67f3d9bd40..9a8851afeb 100644
--- a/wp-admin/includes/plugin.php
+++ b/wp-admin/includes/plugin.php
@@ -2170,7 +2170,7 @@ function add_option_whitelist( $new_options, $options = '' ) {
 				$whitelist_options[ $page ]   = array();
 				$whitelist_options[ $page ][] = $key;
 			} else {
-				$pos = array_search( $key, $whitelist_options[ $page ] );
+				$pos = array_search( $key, $whitelist_options[ $page ], true );
 				if ( false === $pos ) {
 					$whitelist_options[ $page ][] = $key;
 				}
@@ -2202,7 +2202,7 @@ function remove_option_whitelist( $del_options, $options = '' ) {
 	foreach ( $del_options as $page => $keys ) {
 		foreach ( $keys as $key ) {
 			if ( isset( $whitelist_options[ $page ] ) && is_array( $whitelist_options[ $page ] ) ) {
-				$pos = array_search( $key, $whitelist_options[ $page ] );
+				$pos = array_search( $key, $whitelist_options[ $page ], true );
 				if ( false !== $pos ) {
 					unset( $whitelist_options[ $page ][ $pos ] );
 				}
diff --git a/wp-admin/includes/post.php b/wp-admin/includes/post.php
index b2143d61eb..a554932951 100644
--- a/wp-admin/includes/post.php
+++ b/wp-admin/includes/post.php
@@ -548,8 +548,8 @@ function bulk_edit_posts( $post_data = null ) {
 			$children[] = $parent;
 
 			foreach ( $pages as $page ) {
-				if ( $page->ID == $parent ) {
-					$parent = $page->post_parent;
+				if ( (int) $page->ID === $parent ) {
+					$parent = (int) $page->post_parent;
 					break;
 				}
 			}
@@ -568,7 +568,7 @@ function bulk_edit_posts( $post_data = null ) {
 		$post_type_object = get_post_type_object( get_post_type( $post_ID ) );
 
 		if ( ! isset( $post_type_object )
-			|| ( isset( $children ) && in_array( $post_ID, $children ) )
+			|| ( isset( $children ) && in_array( $post_ID, $children, true ) )
 			|| ! current_user_can( 'edit_post', $post_ID )
 		) {
 			$skipped[] = $post_ID;
diff --git a/wp-admin/includes/revision.php b/wp-admin/includes/revision.php
index cbf4eaeb38..ac4f7de00e 100644
--- a/wp-admin/includes/revision.php
+++ b/wp-admin/includes/revision.php
@@ -314,7 +314,7 @@ function wp_prepare_revisions_for_js( $post, $selected_revision_id, $from = null
 	// Now, grab the initial diff.
 	$compare_two_mode = is_numeric( $from );
 	if ( ! $compare_two_mode ) {
-		$found = array_search( $selected_revision_id, array_keys( $revisions ) );
+		$found = array_search( $selected_revision_id, array_keys( $revisions ), true );
 		if ( $found ) {
 			$from = array_keys( array_slice( $revisions, $found - 1, 1, true ) );
 			$from = reset( $from );
diff --git a/wp-admin/includes/screen.php b/wp-admin/includes/screen.php
index db6abfb5ce..75cc14a573 100644
--- a/wp-admin/includes/screen.php
+++ b/wp-admin/includes/screen.php
@@ -128,10 +128,12 @@ function meta_box_prefs( $screen ) {
 					$widget_title = $box['args']['__widget_basename'];
 				}
 
+				$is_hidden = in_array( $box['id'], $hidden, true );
+
 				printf(
 					'<label for="%1$s-hide"><input class="hide-postbox-tog" name="%1$s-hide" type="checkbox" id="%1$s-hide" value="%1$s" %2$s />%3$s</label>',
 					esc_attr( $box['id'] ),
-					checked( in_array( $box['id'], $hidden, true ), false, false ),
+					checked( $is_hidden, false, false ),
 					$widget_title
 				);
 			}
diff --git a/wp-admin/includes/template.php b/wp-admin/includes/template.php
index 882af9e149..c140849f6e 100644
--- a/wp-admin/includes/template.php
+++ b/wp-admin/includes/template.php
@@ -171,7 +171,7 @@ function wp_terms_checklist( $post_id = 0, $args = array() ) {
 		$keys               = array_keys( $categories );
 
 		foreach ( $keys as $k ) {
-			if ( in_array( $categories[ $k ]->term_id, $args['selected_cats'] ) ) {
+			if ( in_array( $categories[ $k ]->term_id, $args['selected_cats'], true ) ) {
 				$checked_categories[] = $categories[ $k ];
 				unset( $categories[ $k ] );
 			}
@@ -228,13 +228,14 @@ function wp_popular_terms_checklist( $taxonomy, $default = 0, $number = 10, $ech
 	$tax = get_taxonomy( $taxonomy );
 
 	$popular_ids = array();
+
 	foreach ( (array) $terms as $term ) {
 		$popular_ids[] = $term->term_id;
 		if ( ! $echo ) { // Hack for Ajax use.
 			continue;
 		}
 		$id      = "popular-$taxonomy-$term->term_id";
-		$checked = in_array( $term->term_id, $checked_terms ) ? 'checked="checked"' : '';
+		$checked = in_array( $term->term_id, $checked_terms, true ) ? 'checked="checked"' : '';
 		?>
 
 		<li id="<?php echo $id; ?>" class="popular-category">
@@ -291,7 +292,7 @@ function wp_link_category_checklist( $link_id = 0 ) {
 
 		/** This filter is documented in wp-includes/category-template.php */
 		$name    = esc_html( apply_filters( 'the_category', $category->name, '', '' ) );
-		$checked = in_array( $cat_id, $checked_categories ) ? ' checked="checked"' : '';
+		$checked = in_array( $cat_id, $checked_categories, true ) ? ' checked="checked"' : '';
 		echo '<li id="link-category-', $cat_id, '"><label for="in-link-category-', $cat_id, '" class="selectit"><input value="', $cat_id, '" type="checkbox" name="link_category[]" id="in-link-category-', $cat_id, '"', $checked, '/> ', $name, '</label></li>';
 	}
 }
@@ -339,6 +340,7 @@ function get_inline_data( $post ) {
 	}
 
 	$taxonomy_names = get_object_taxonomies( $post->post_type );
+
 	foreach ( $taxonomy_names as $taxonomy_name ) {
 		$taxonomy = get_taxonomy( $taxonomy_name );
 
@@ -721,7 +723,6 @@ function meta_form( $post = null ) {
 <select id="metakeyselect" name="metakeyselect">
 <option value="#NONE#"><?php _e( '&mdash; Select &mdash;' ); ?></option>
 		<?php
-
 		foreach ( $keys as $key ) {
 			if ( is_protected_meta( $key, 'post' ) || ! current_user_can( 'add_post_meta', $post->ID, $key ) ) {
 				continue;
@@ -834,6 +835,7 @@ function touch_time( $edit = 1, $for_post = 1, $tab_index = 0, $multi = 0 ) {
 	}
 
 	echo "\n\n";
+
 	$map = array(
 		'mm' => array( $mm, $cur_mm ),
 		'jj' => array( $jj, $cur_jj ),
@@ -841,6 +843,7 @@ function touch_time( $edit = 1, $for_post = 1, $tab_index = 0, $multi = 0 ) {
 		'hh' => array( $hh, $cur_hh ),
 		'mn' => array( $mn, $cur_mn ),
 	);
+
 	foreach ( $map as $timeunit => $value ) {
 		list( $unit, $curr ) = $value;
 
@@ -868,7 +871,9 @@ function touch_time( $edit = 1, $for_post = 1, $tab_index = 0, $multi = 0 ) {
  */
 function page_template_dropdown( $default = '', $post_type = 'page' ) {
 	$templates = get_page_templates( null, $post_type );
+
 	ksort( $templates );
+
 	foreach ( array_keys( $templates ) as $template ) {
 		$selected = selected( $default, $templates[ $template ], false );
 		echo "\n\t<option value='" . esc_attr( $templates[ $template ] ) . "' $selected>" . esc_html( $template ) . '</option>';
@@ -1195,11 +1200,13 @@ function _get_plugin_from_callback( $callback ) {
 		// Only show errors if the meta box was registered by a plugin.
 		$filename   = wp_normalize_path( $reflection->getFileName() );
 		$plugin_dir = wp_normalize_path( WP_PLUGIN_DIR );
+
 		if ( strpos( $filename, $plugin_dir ) === 0 ) {
 			$filename = str_replace( $plugin_dir, '', $filename );
 			$filename = preg_replace( '|^/([^/]*/).*$|', '\\1', $filename );
 
 			$plugins = get_plugins();
+
 			foreach ( $plugins as $name => $plugin ) {
 				if ( strpos( $name, $filename ) === 0 ) {
 					return $plugin;
@@ -1249,6 +1256,7 @@ function do_meta_boxes( $screen, $context, $object ) {
 	// Grab the ones the user has manually sorted.
 	// Pull them out of their previous context/priority and into the one the user chose.
 	$sorted = get_user_option( "meta-box-order_$page" );
+
 	if ( ! $already_sorted && $sorted ) {
 		foreach ( $sorted as $box_context => $ids ) {
 			foreach ( explode( ',', $ids ) as $id ) {
@@ -1780,11 +1788,13 @@ function get_settings_errors( $setting = '', $sanitize = false ) {
 	// Filter the results to those of a specific setting if one was set.
 	if ( $setting ) {
 		$setting_errors = array();
+
 		foreach ( (array) $wp_settings_errors as $key => $details ) {
 			if ( $setting == $details['setting'] ) {
 				$setting_errors[] = $wp_settings_errors[ $key ];
 			}
 		}
+
 		return $setting_errors;
 	}
 
@@ -1833,6 +1843,7 @@ function settings_errors( $setting = '', $sanitize = false, $hide_on_update = fa
 	}
 
 	$output = '';
+
 	foreach ( $settings_errors as $key => $details ) {
 		if ( 'updated' === $details['type'] ) {
 			$details['type'] = 'success';
@@ -1855,6 +1866,7 @@ function settings_errors( $setting = '', $sanitize = false, $hide_on_update = fa
 		$output .= "<p><strong>{$details['message']}</strong></p>";
 		$output .= "</div> \n";
 	}
+
 	echo $output;
 }
 
@@ -2084,6 +2096,7 @@ function _post_states( $post, $echo = true ) {
 		$i           = 0;
 
 		$post_states_string .= ' &mdash; ';
+
 		foreach ( $post_states as $state ) {
 			++$i;
 			( $i == $state_count ) ? $sep = '' : $sep = ', ';
@@ -2188,7 +2201,7 @@ function _media_states( $post ) {
 		if ( is_random_header_image() ) {
 			$header_images = wp_list_pluck( get_uploaded_header_images(), 'attachment_id' );
 
-			if ( $meta_header == $stylesheet && in_array( $post->ID, $header_images ) ) {
+			if ( $meta_header == $stylesheet && in_array( $post->ID, $header_images, true ) ) {
 				$media_states[] = __( 'Header Image' );
 			}
 		} else {
@@ -2242,7 +2255,9 @@ function _media_states( $post ) {
 	if ( ! empty( $media_states ) ) {
 		$state_count = count( $media_states );
 		$i           = 0;
+
 		echo ' &mdash; ';
+
 		foreach ( $media_states as $state ) {
 			++$i;
 			( $i == $state_count ) ? $sep = '' : $sep = ', ';
@@ -2369,12 +2384,15 @@ function get_submit_button( $text = '', $type = 'primary large', $name = 'submit
 
 	$button_shorthand = array( 'primary', 'small', 'large' );
 	$classes          = array( 'button' );
+
 	foreach ( $type as $t ) {
 		if ( 'secondary' === $t || 'button-secondary' === $t ) {
 			continue;
 		}
+
 		$classes[] = in_array( $t, $button_shorthand, true ) ? 'button-' . $t : $t;
 	}
+
 	// Remove empty items, remove duplicate items, and finally build a string.
 	$class = implode( ' ', array_unique( array_filter( $classes ) ) );
 
diff --git a/wp-admin/nav-menus.php b/wp-admin/nav-menus.php
index 9e92d43619..311e5b4d26 100644
--- a/wp-admin/nav-menus.php
+++ b/wp-admin/nav-menus.php
@@ -104,8 +104,11 @@ switch ( $action ) {
 							$next_item_data['menu_item_parent'] != $menu_item_data['menu_item_parent']
 						)
 					) {
-
-						$parent_db_id = in_array( $menu_item_data['menu_item_parent'], $orders_to_dbids ) ? (int) $menu_item_data['menu_item_parent'] : 0;
+						if ( in_array( (int) $menu_item_data['menu_item_parent'], $orders_to_dbids, true ) ) {
+							$parent_db_id = (int) $menu_item_data['menu_item_parent'];
+						} else {
+							$parent_db_id = 0;
+						}
 
 						$parent_object = wp_setup_nav_menu_item( get_post( $parent_db_id ) );
 
@@ -131,7 +134,7 @@ switch ( $action ) {
 					// The item is last but still has a parent, so bubble up.
 				} elseif (
 					! empty( $menu_item_data['menu_item_parent'] ) &&
-					in_array( $menu_item_data['menu_item_parent'], $orders_to_dbids )
+					in_array( (int) $menu_item_data['menu_item_parent'], $orders_to_dbids, true )
 				) {
 					$menu_item_data['menu_item_parent'] = (int) get_post_meta( $menu_item_data['menu_item_parent'], '_menu_item_menu_item_parent', true );
 					update_post_meta( $menu_item_data['ID'], '_menu_item_menu_item_parent', (int) $menu_item_data['menu_item_parent'] );
@@ -168,11 +171,16 @@ switch ( $action ) {
 					// If this menu item is a child of the previous.
 					if (
 						! empty( $menu_item_data['menu_item_parent'] ) &&
-						in_array( $menu_item_data['menu_item_parent'], array_keys( $dbids_to_orders ) ) &&
+						in_array( (int) $menu_item_data['menu_item_parent'], array_keys( $dbids_to_orders ), true ) &&
 						isset( $orders_to_dbids[ $dbids_to_orders[ $menu_item_id ] - 1 ] ) &&
 						( $menu_item_data['menu_item_parent'] == $orders_to_dbids[ $dbids_to_orders[ $menu_item_id ] - 1 ] )
 					) {
-						$parent_db_id  = in_array( $menu_item_data['menu_item_parent'], $orders_to_dbids ) ? (int) $menu_item_data['menu_item_parent'] : 0;
+						if ( in_array( (int) $menu_item_data['menu_item_parent'], $orders_to_dbids, true ) ) {
+							$parent_db_id = (int) $menu_item_data['menu_item_parent'];
+						} else {
+							$parent_db_id = 0;
+						}
+
 						$parent_object = wp_setup_nav_menu_item( get_post( $parent_db_id ) );
 
 						if ( ! is_wp_error( $parent_object ) ) {
@@ -198,7 +206,7 @@ switch ( $action ) {
 								! empty( $orders_to_dbids[ $dbids_to_orders[ $parent_db_id ] - 1 ] )
 							) {
 								$_possible_parent_id = (int) get_post_meta( $orders_to_dbids[ $dbids_to_orders[ $parent_db_id ] - 1 ], '_menu_item_menu_item_parent', true );
-								if ( in_array( $_possible_parent_id, array_keys( $dbids_to_orders ) ) ) {
+								if ( in_array( $_possible_parent_id, array_keys( $dbids_to_orders ), true ) ) {
 									$menu_item_data['menu_item_parent'] = $_possible_parent_id;
 								} else {
 									$menu_item_data['menu_item_parent'] = 0;
@@ -225,7 +233,7 @@ switch ( $action ) {
 					} elseif (
 						empty( $menu_item_data['menu_order'] ) ||
 						empty( $menu_item_data['menu_item_parent'] ) ||
-						! in_array( $menu_item_data['menu_item_parent'], array_keys( $dbids_to_orders ) ) ||
+						! in_array( (int) $menu_item_data['menu_item_parent'], array_keys( $dbids_to_orders ), true ) ||
 						empty( $orders_to_dbids[ $dbids_to_orders[ $menu_item_id ] - 1 ] ) ||
 						$orders_to_dbids[ $dbids_to_orders[ $menu_item_id ] - 1 ] != $menu_item_data['menu_item_parent']
 					) {
@@ -800,9 +808,10 @@ require_once ABSPATH . 'wp-admin/admin-header.php';
 						<?php
 						echo esc_html( $_nav_menu->truncated_name );
 
-						if ( ! empty( $menu_locations ) && in_array( $_nav_menu->term_id, $menu_locations ) ) {
+						if ( ! empty( $menu_locations ) && in_array( $_nav_menu->term_id, $menu_locations, true ) ) {
 							$locations_assigned_to_this_menu = array();
-							foreach ( array_keys( $menu_locations, $_nav_menu->term_id ) as $menu_location_key ) {
+
+							foreach ( array_keys( $menu_locations, $_nav_menu->term_id, true ) as $menu_location_key ) {
 								if ( isset( $locations[ $menu_location_key ] ) ) {
 									$locations_assigned_to_this_menu[] = $locations[ $menu_location_key ];
 								}
@@ -815,7 +824,9 @@ require_once ABSPATH . 'wp-admin/admin-header.php';
 							 *
 							 * @param int $locations Number of menu locations to list. Default 3.
 							 */
-							$assigned_locations = array_slice( $locations_assigned_to_this_menu, 0, absint( apply_filters( 'wp_nav_locations_listed_per_menu', 3 ) ) );
+							$locations_listed_per_menu = absint( apply_filters( 'wp_nav_locations_listed_per_menu', 3 ) );
+
+							$assigned_locations = array_slice( $locations_assigned_to_this_menu, 0, $locations_listed_per_menu );
 
 							// Adds ellipses following the number of locations defined in $assigned_locations.
 							if ( ! empty( $assigned_locations ) ) {
@@ -956,9 +967,10 @@ require_once ABSPATH . 'wp-admin/admin-header.php';
 								<?php
 								if ( ! isset( $auto_add ) ) {
 									$auto_add = get_option( 'nav_menu_options' );
+
 									if ( ! isset( $auto_add['auto_add'] ) ) {
 										$auto_add = false;
-									} elseif ( false !== array_search( $nav_menu_selected_id, $auto_add['auto_add'] ) ) {
+									} elseif ( false !== array_search( $nav_menu_selected_id, $auto_add['auto_add'], true ) ) {
 										$auto_add = true;
 									} else {
 										$auto_add = false;
diff --git a/wp-admin/network/site-info.php b/wp-admin/network/site-info.php
index c6a69114f2..7bba7da934 100644
--- a/wp-admin/network/site-info.php
+++ b/wp-admin/network/site-info.php
@@ -72,8 +72,9 @@ if ( isset( $_REQUEST['action'] ) && 'update-site' == $_REQUEST['action'] ) {
 
 	$existing_details     = get_site( $id );
 	$blog_data_checkboxes = array( 'public', 'archived', 'spam', 'mature', 'deleted' );
+
 	foreach ( $blog_data_checkboxes as $c ) {
-		if ( ! in_array( $existing_details->$c, array( 0, 1 ) ) ) {
+		if ( ! in_array( (int) $existing_details->$c, array( 0, 1 ), true ) ) {
 			$blog_data[ $c ] = $existing_details->$c;
 		} else {
 			$blog_data[ $c ] = isset( $_POST['blog'][ $c ] ) ? 1 : 0;
@@ -194,7 +195,7 @@ if ( ! empty( $messages ) ) {
 			<fieldset>
 			<legend class="screen-reader-text"><?php _e( 'Set site attributes' ); ?></legend>
 			<?php foreach ( $attribute_fields as $field_key => $field_label ) : ?>
-				<label><input type="checkbox" name="blog[<?php echo $field_key; ?>]" value="1" <?php checked( (bool) $details->$field_key, true ); ?> <?php disabled( ! in_array( $details->$field_key, array( 0, 1 ) ) ); ?> />
+				<label><input type="checkbox" name="blog[<?php echo $field_key; ?>]" value="1" <?php checked( (bool) $details->$field_key, true ); ?> <?php disabled( ! in_array( (int) $details->$field_key, array( 0, 1 ), true ) ); ?> />
 				<?php echo $field_label; ?></label><br/>
 			<?php endforeach; ?>
 			<fieldset>
diff --git a/wp-admin/users.php b/wp-admin/users.php
index b8eb3a45c0..04164d7179 100644
--- a/wp-admin/users.php
+++ b/wp-admin/users.php
@@ -237,7 +237,7 @@ switch ( $wp_list_table->current_action() ) {
 
 		$all_userids = $userids;
 
-		if ( in_array( $current_user->ID, $userids ) ) {
+		if ( in_array( $current_user->ID, $userids, true ) ) {
 			$userids = array_diff( $userids, array( $current_user->ID ) );
 		}
 
diff --git a/wp-includes/class-http.php b/wp-includes/class-http.php
index 561a9ce443..fd759b7347 100644
--- a/wp-includes/class-http.php
+++ b/wp-includes/class-http.php
@@ -1041,7 +1041,7 @@ class WP_Http {
 
 		// POST requests should not POST to a redirected location.
 		if ( 'POST' == $args['method'] ) {
-			if ( in_array( $response['response']['code'], array( 302, 303 ) ) ) {
+			if ( in_array( $response['response']['code'], array( 302, 303 ), true ) ) {
 				$args['method'] = 'GET';
 			}
 		}
diff --git a/wp-includes/class-walker-page.php b/wp-includes/class-walker-page.php
index 0b77c422bf..557bf309b0 100644
--- a/wp-includes/class-walker-page.php
+++ b/wp-includes/class-walker-page.php
@@ -122,12 +122,14 @@ class Walker_Page extends Walker {
 
 		if ( ! empty( $current_page ) ) {
 			$_current_page = get_post( $current_page );
-			if ( $_current_page && in_array( $page->ID, $_current_page->ancestors ) ) {
+
+			if ( $_current_page && in_array( $page->ID, $_current_page->ancestors, true ) ) {
 				$css_class[] = 'current_page_ancestor';
 			}
+
 			if ( $page->ID == $current_page ) {
 				$css_class[] = 'current_page_item';
-			} elseif ( $_current_page && $page->ID == $_current_page->post_parent ) {
+			} elseif ( $_current_page && $page->ID === $_current_page->post_parent ) {
 				$css_class[] = 'current_page_parent';
 			}
 		} elseif ( get_option( 'page_for_posts' ) == $page->ID ) {
diff --git a/wp-includes/class-wp-http-cookie.php b/wp-includes/class-wp-http-cookie.php
index 24bfbbaf94..fb3861383e 100644
--- a/wp-includes/class-wp-http-cookie.php
+++ b/wp-includes/class-wp-http-cookie.php
@@ -192,7 +192,7 @@ class WP_Http_Cookie {
 		}
 
 		// Port - supports "port-lists" in the format: "80,8000,8080".
-		if ( ! empty( $port ) && ! in_array( $url['port'], explode( ',', $port ) ) ) {
+		if ( ! empty( $port ) && ! in_array( $url['port'], array_map( 'intval', explode( ',', $port ) ), true ) ) {
 			return false;
 		}
 
diff --git a/wp-includes/class-wp-http-curl.php b/wp-includes/class-wp-http-curl.php
index 8225a290f4..df62fcc12b 100644
--- a/wp-includes/class-wp-http-curl.php
+++ b/wp-includes/class-wp-http-curl.php
@@ -238,7 +238,7 @@ class WP_Http_Curl {
 				curl_close( $handle );
 				return new WP_Error( 'http_request_failed', $curl_error );
 			}
-			if ( in_array( curl_getinfo( $handle, CURLINFO_HTTP_CODE ), array( 301, 302 ) ) ) {
+			if ( in_array( curl_getinfo( $handle, CURLINFO_HTTP_CODE ), array( 301, 302 ), true ) ) {
 				curl_close( $handle );
 				return new WP_Error( 'http_request_failed', __( 'Too many redirects.' ) );
 			}
@@ -286,7 +286,7 @@ class WP_Http_Curl {
 					return new WP_Error( 'http_request_failed', $curl_error );
 				}
 			}
-			if ( in_array( curl_getinfo( $handle, CURLINFO_HTTP_CODE ), array( 301, 302 ) ) ) {
+			if ( in_array( curl_getinfo( $handle, CURLINFO_HTTP_CODE ), array( 301, 302 ), true ) ) {
 				curl_close( $handle );
 				return new WP_Error( 'http_request_failed', __( 'Too many redirects.' ) );
 			}
diff --git a/wp-includes/class-wp-query.php b/wp-includes/class-wp-query.php
index 856a6fbc98..b72c9c35aa 100644
--- a/wp-includes/class-wp-query.php
+++ b/wp-includes/class-wp-query.php
@@ -3137,7 +3137,7 @@ class WP_Query {
 			$sticky_offset = 0;
 			// Loop over posts and relocate stickies to the front.
 			for ( $i = 0; $i < $num_posts; $i++ ) {
-				if ( in_array( $this->posts[ $i ]->ID, $sticky_posts ) ) {
+				if ( in_array( $this->posts[ $i ]->ID, $sticky_posts, true ) ) {
 					$sticky_post = $this->posts[ $i ];
 					// Remove sticky from current position.
 					array_splice( $this->posts, $i, 1 );
@@ -3146,7 +3146,7 @@ class WP_Query {
 					// Increment the sticky offset. The next sticky will be placed at this offset.
 					$sticky_offset++;
 					// Remove post from sticky posts array.
-					$offset = array_search( $sticky_post->ID, $sticky_posts );
+					$offset = array_search( $sticky_post->ID, $sticky_posts, true );
 					unset( $sticky_posts[ $offset ] );
 				}
 			}
diff --git a/wp-includes/class-wp-theme.php b/wp-includes/class-wp-theme.php
index 190d024a0b..d9368317ae 100644
--- a/wp-includes/class-wp-theme.php
+++ b/wp-includes/class-wp-theme.php
@@ -276,7 +276,7 @@ final class WP_Theme implements ArrayAccess {
 			$this->headers = get_file_data( $this->theme_root . '/' . $theme_file, self::$file_headers, 'theme' );
 			// Default themes always trump their pretenders.
 			// Properly identify default themes that are inside a directory within wp-content/themes.
-			$default_theme_slug = array_search( $this->headers['Name'], self::$default_themes );
+			$default_theme_slug = array_search( $this->headers['Name'], self::$default_themes, true );
 			if ( $default_theme_slug ) {
 				if ( basename( $this->stylesheet ) != $default_theme_slug ) {
 					$this->headers['Name'] .= '/' . $this->stylesheet;
diff --git a/wp-includes/customize/class-wp-customize-nav-menu-setting.php b/wp-includes/customize/class-wp-customize-nav-menu-setting.php
index c0783bf686..1b0de422ab 100644
--- a/wp-includes/customize/class-wp-customize-nav-menu-setting.php
+++ b/wp-includes/customize/class-wp-customize-nav-menu-setting.php
@@ -179,7 +179,7 @@ class WP_Customize_Nav_Menu_Setting extends WP_Customize_Setting {
 					$value['auto_add'] = false;
 
 					if ( isset( $nav_menu_options['auto_add'] ) && is_array( $nav_menu_options['auto_add'] ) ) {
-						$value['auto_add'] = in_array( $term->term_id, $nav_menu_options['auto_add'] );
+						$value['auto_add'] = in_array( $term->term_id, $nav_menu_options['auto_add'], true );
 					}
 				}
 			}
@@ -188,6 +188,7 @@ class WP_Customize_Nav_Menu_Setting extends WP_Customize_Setting {
 				$value = $this->default;
 			}
 		}
+
 		return $value;
 	}
 
@@ -602,7 +603,8 @@ class WP_Customize_Nav_Menu_Setting extends WP_Customize_Setting {
 			$nav_menu_options['auto_add'] = array();
 		}
 
-		$i = array_search( $menu_id, $nav_menu_options['auto_add'] );
+		$i = array_search( $menu_id, $nav_menu_options['auto_add'], true );
+
 		if ( $auto_add && false === $i ) {
 			array_push( $nav_menu_options['auto_add'], $this->term_id );
 		} elseif ( ! $auto_add && false !== $i ) {
diff --git a/wp-includes/general-template.php b/wp-includes/general-template.php
index d136c357b7..437dd4dc1c 100644
--- a/wp-includes/general-template.php
+++ b/wp-includes/general-template.php
@@ -2180,9 +2180,10 @@ function get_calendar( $initial = true, $echo = true ) {
 		AND post_date <= '{$thisyear}-{$thismonth}-{$last_day} 23:59:59'",
 		ARRAY_N
 	);
+
 	if ( $dayswithposts ) {
 		foreach ( (array) $dayswithposts as $daywith ) {
-			$daywithpost[] = $daywith[0];
+			$daywithpost[] = (int) $daywith[0];
 		}
 	}
 
@@ -2209,7 +2210,7 @@ function get_calendar( $initial = true, $echo = true ) {
 			$calendar_output .= '<td>';
 		}
 
-		if ( in_array( $day, $daywithpost ) ) {
+		if ( in_array( $day, $daywithpost, true ) ) {
 			// Any posts today?
 			$date_format = gmdate( _x( 'F j, Y', 'daily archives date format' ), strtotime( "{$thisyear}-{$thismonth}-{$day}" ) );
 			/* translators: Post calendar label. %s: Date. */
@@ -2223,6 +2224,7 @@ function get_calendar( $initial = true, $echo = true ) {
 		} else {
 			$calendar_output .= $day;
 		}
+
 		$calendar_output .= '</td>';
 
 		if ( 6 == calendar_week_mod( gmdate( 'w', mktime( 0, 0, 0, $thismonth, $day, $thisyear ) ) - $week_begins ) ) {
@@ -2234,6 +2236,7 @@ function get_calendar( $initial = true, $echo = true ) {
 	if ( 0 != $pad && 7 != $pad ) {
 		$calendar_output .= "\n\t\t" . '<td class="pad" colspan="' . esc_attr( $pad ) . '">&nbsp;</td>';
 	}
+
 	$calendar_output .= "\n\t</tr>\n\t</tbody>";
 
 	$calendar_output .= "\n\t</table>";
diff --git a/wp-includes/link-template.php b/wp-includes/link-template.php
index 5345ec4281..9dbbf4931f 100644
--- a/wp-includes/link-template.php
+++ b/wp-includes/link-template.php
@@ -3687,13 +3687,15 @@ function get_dashboard_url( $user_id = 0, $path = '', $scheme = 'admin' ) {
 	$user_id = $user_id ? (int) $user_id : get_current_user_id();
 
 	$blogs = get_blogs_of_user( $user_id );
+
 	if ( is_multisite() && ! user_can( $user_id, 'manage_network' ) && empty( $blogs ) ) {
 		$url = user_admin_url( $path, $scheme );
 	} elseif ( ! is_multisite() ) {
 		$url = admin_url( $path, $scheme );
 	} else {
 		$current_blog = get_current_blog_id();
-		if ( $current_blog && ( user_can( $user_id, 'manage_network' ) || in_array( $current_blog, array_keys( $blogs ) ) ) ) {
+
+		if ( $current_blog && ( user_can( $user_id, 'manage_network' ) || in_array( $current_blog, array_keys( $blogs ), true ) ) ) {
 			$url = admin_url( $path, $scheme );
 		} else {
 			$active = get_active_blog_for_user( $user_id );
diff --git a/wp-includes/nav-menu-template.php b/wp-includes/nav-menu-template.php
index 9dd1601ee5..d49dbeed02 100644
--- a/wp-includes/nav-menu-template.php
+++ b/wp-includes/nav-menu-template.php
@@ -392,7 +392,9 @@ function _wp_menu_item_classes_by_context( &$menu_items ) {
 		}
 
 		// If the menu item corresponds to a taxonomy term for the currently queried non-hierarchical post object.
-		if ( $wp_query->is_singular && 'taxonomy' == $menu_item->type && in_array( $menu_item->object_id, $possible_object_parents ) ) {
+		if ( $wp_query->is_singular && 'taxonomy' == $menu_item->type
+			&& in_array( (int) $menu_item->object_id, $possible_object_parents, true )
+		) {
 			$active_parent_object_ids[] = (int) $menu_item->object_id;
 			$active_parent_item_ids[]   = (int) $menu_item->db_id;
 			$active_object              = $queried_object->post_type;
@@ -404,7 +406,8 @@ function _wp_menu_item_classes_by_context( &$menu_items ) {
 				( ! empty( $home_page_id ) && 'post_type' == $menu_item->type && $wp_query->is_home && $home_page_id == $menu_item->object_id )
 				|| ( 'post_type' == $menu_item->type && $wp_query->is_singular )
 				|| ( 'taxonomy' == $menu_item->type
-					&& ( $wp_query->is_category || $wp_query->is_tag || $wp_query->is_tax ) && $queried_object->taxonomy == $menu_item->object )
+					&& ( $wp_query->is_category || $wp_query->is_tag || $wp_query->is_tax )
+					&& $queried_object->taxonomy == $menu_item->object )
 			)
 		) {
 			$classes[]                   = 'current-menu-item';
@@ -525,7 +528,7 @@ function _wp_menu_item_classes_by_context( &$menu_items ) {
 					'post_type' == $parent_item->type
 					&& ! empty( $queried_object->post_type )
 					&& is_post_type_hierarchical( $queried_object->post_type )
-					&& in_array( $parent_item->object_id, $queried_object->ancestors )
+					&& in_array( (int) $parent_item->object_id, $queried_object->ancestors, true )
 					&& $parent_item->object != $queried_object->ID
 				) ||
 
@@ -533,7 +536,7 @@ function _wp_menu_item_classes_by_context( &$menu_items ) {
 				(
 					'taxonomy' == $parent_item->type
 					&& isset( $possible_taxonomy_ancestors[ $parent_item->object ] )
-					&& in_array( $parent_item->object_id, $possible_taxonomy_ancestors[ $parent_item->object ] )
+					&& in_array( (int) $parent_item->object_id, $possible_taxonomy_ancestors[ $parent_item->object ], true )
 					&& (
 						! isset( $queried_object->term_id ) ||
 						$parent_item->object_id != $queried_object->term_id
diff --git a/wp-includes/post.php b/wp-includes/post.php
index 10eee1d25f..47c5648ca6 100644
--- a/wp-includes/post.php
+++ b/wp-includes/post.php
@@ -2284,7 +2284,12 @@ function is_sticky( $post_id = 0 ) {
 
 	$stickies = get_option( 'sticky_posts' );
 
-	$is_sticky = is_array( $stickies ) && in_array( $post_id, $stickies );
+	if ( is_array( $stickies ) ) {
+		$stickies  = array_map( 'intval', $stickies );
+		$is_sticky = in_array( $post_id, $stickies, true );
+	} else {
+		$is_sticky = false;
+	}
 
 	/**
 	 * Filters whether a post is sticky.
@@ -2511,13 +2516,16 @@ function sanitize_post_field( $field, $value, $post_id, $context = 'display' ) {
  * @param int $post_id Post ID.
  */
 function stick_post( $post_id ) {
+	$post_id  = (int) $post_id;
 	$stickies = get_option( 'sticky_posts' );
 
 	if ( ! is_array( $stickies ) ) {
-		$stickies = array( $post_id );
+		$stickies = array();
 	}
 
-	if ( ! in_array( $post_id, $stickies ) ) {
+	$stickies = array_map( 'intval', $stickies );
+
+	if ( ! in_array( $post_id, $stickies, true ) ) {
 		$stickies[] = $post_id;
 	}
 
@@ -2545,17 +2553,20 @@ function stick_post( $post_id ) {
  * @param int $post_id Post ID.
  */
 function unstick_post( $post_id ) {
+	$post_id  = (int) $post_id;
 	$stickies = get_option( 'sticky_posts' );
 
 	if ( ! is_array( $stickies ) ) {
 		return;
 	}
 
-	if ( ! in_array( $post_id, $stickies ) ) {
+	$stickies = array_map( 'intval', $stickies );
+
+	if ( ! in_array( $post_id, $stickies, true ) ) {
 		return;
 	}
 
-	$offset = array_search( $post_id, $stickies );
+	$offset = array_search( $post_id, $stickies, true );
 	if ( false === $offset ) {
 		return;
 	}
@@ -2841,8 +2852,10 @@ function wp_match_mime_types( $wildcard_mime_types, $real_mime_types ) {
 	foreach ( (array) $wildcard_mime_types as $type ) {
 		$mimes = array_map( 'trim', explode( ',', $type ) );
 		foreach ( $mimes as $mime ) {
-			$regex                 = str_replace( '__wildcard__', $wild, preg_quote( str_replace( '*', '__wildcard__', $mime ) ) );
+			$regex = str_replace( '__wildcard__', $wild, preg_quote( str_replace( '*', '__wildcard__', $mime ) ) );
+
 			$patternses[][ $type ] = "^$regex$";
+
 			if ( false === strpos( $mime, '/' ) ) {
 				$patternses[][ $type ] = "^$regex/";
 				$patternses[][ $type ] = $regex;
@@ -2854,12 +2867,15 @@ function wp_match_mime_types( $wildcard_mime_types, $real_mime_types ) {
 	foreach ( $patternses as $patterns ) {
 		foreach ( $patterns as $type => $pattern ) {
 			foreach ( (array) $real_mime_types as $real ) {
-				if ( preg_match( "#$pattern#", $real ) && ( empty( $matches[ $type ] ) || false === array_search( $real, $matches[ $type ] ) ) ) {
+				if ( preg_match( "#$pattern#", $real )
+					&& ( empty( $matches[ $type ] ) || false === array_search( $real, $matches[ $type ], true ) )
+				) {
 					$matches[ $type ][] = $real;
 				}
 			}
 		}
 	}
+
 	return $matches;
 }
 
@@ -2914,9 +2930,11 @@ function wp_post_mime_type_where( $post_mime_types, $table_alias = '' ) {
 			$wheres[] = empty( $table_alias ) ? "post_mime_type = '$mime_pattern'" : "$table_alias.post_mime_type = '$mime_pattern'";
 		}
 	}
+
 	if ( ! empty( $wheres ) ) {
 		$where = ' AND (' . join( ' OR ', $wheres ) . ') ';
 	}
+
 	return $where;
 }
 
@@ -4436,15 +4454,16 @@ function wp_unique_post_slug( $slug, $post_ID, $post_status, $post_type, $post_p
 		$check_sql       = "SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND post_type = %s AND ID != %d LIMIT 1";
 		$post_name_check = $wpdb->get_var( $wpdb->prepare( $check_sql, $slug, $post_type, $post_ID ) );
 
+		$post = get_post( $post_ID );
+
 		// Prevent new post slugs that could result in URLs that conflict with date archives.
-		$post                        = get_post( $post_ID );
 		$conflicts_with_date_archive = false;
 		if ( 'post' === $post_type && ( ! $post || $post->post_name !== $slug ) && preg_match( '/^[0-9]+$/', $slug ) ) {
 			$slug_num = intval( $slug );
 
 			if ( $slug_num ) {
 				$permastructs   = array_values( array_filter( explode( '/', get_option( 'permalink_structure' ) ) ) );
-				$postname_index = array_search( '%postname%', $permastructs );
+				$postname_index = array_search( '%postname%', $permastructs, true );
 
 				/*
 				* Potential date clashes are as follows:
@@ -5500,7 +5519,7 @@ function get_pages( $args = array() ) {
 
 		$num_pages = count( $pages );
 		for ( $i = 0; $i < $num_pages; $i++ ) {
-			if ( in_array( $pages[ $i ]->ID, $exclude ) ) {
+			if ( in_array( $pages[ $i ]->ID, $exclude, true ) ) {
 				unset( $pages[ $i ] );
 			}
 		}
@@ -5811,7 +5830,8 @@ function wp_delete_attachment_files( $post_id, $meta, $backup_sizes, $file ) {
  */
 function wp_get_attachment_metadata( $attachment_id = 0, $unfiltered = false ) {
 	$attachment_id = (int) $attachment_id;
-	$post          = get_post( $attachment_id );
+
+	$post = get_post( $attachment_id );
 	if ( ! $post ) {
 		return false;
 	}
@@ -5845,7 +5865,8 @@ function wp_get_attachment_metadata( $attachment_id = 0, $unfiltered = false ) {
  */
 function wp_update_attachment_metadata( $attachment_id, $data ) {
 	$attachment_id = (int) $attachment_id;
-	$post          = get_post( $attachment_id );
+
+	$post = get_post( $attachment_id );
 	if ( ! $post ) {
 		return false;
 	}
@@ -5878,7 +5899,8 @@ function wp_update_attachment_metadata( $attachment_id, $data ) {
  */
 function wp_get_attachment_url( $attachment_id = 0 ) {
 	$attachment_id = (int) $attachment_id;
-	$post          = get_post( $attachment_id );
+
+	$post = get_post( $attachment_id );
 	if ( ! $post ) {
 		return false;
 	}
diff --git a/wp-includes/rewrite.php b/wp-includes/rewrite.php
index 1c91e137ee..c704bdd317 100644
--- a/wp-includes/rewrite.php
+++ b/wp-includes/rewrite.php
@@ -596,7 +596,7 @@ function url_to_postid( $url ) {
 			parse_str( $query, $query_vars );
 			$query = array();
 			foreach ( (array) $query_vars as $key => $value ) {
-				if ( in_array( $key, $wp->public_query_vars, true ) ) {
+				if ( in_array( (string) $key, $wp->public_query_vars, true ) ) {
 					$query[ $key ] = $value;
 					if ( isset( $post_type_query_vars[ $key ] ) ) {
 						$query['post_type'] = $post_type_query_vars[ $key ];
diff --git a/wp-includes/taxonomy.php b/wp-includes/taxonomy.php
index 245a63c970..d240740ff2 100644
--- a/wp-includes/taxonomy.php
+++ b/wp-includes/taxonomy.php
@@ -2468,16 +2468,20 @@ function wp_set_object_terms( $object_id, $terms, $taxonomy, $append = false ) {
 		}
 
 		$term_info = term_exists( $term, $taxonomy );
+
 		if ( ! $term_info ) {
 			// Skip if a non-existent term ID is passed.
 			if ( is_int( $term ) ) {
 				continue;
 			}
+
 			$term_info = wp_insert_term( $term, $taxonomy );
 		}
+
 		if ( is_wp_error( $term_info ) ) {
 			return $term_info;
 		}
+
 		$term_ids[] = $term_info['term_id'];
 		$tt_id      = $term_info['term_taxonomy_id'];
 		$tt_ids[]   = $tt_id;
@@ -2497,6 +2501,7 @@ function wp_set_object_terms( $object_id, $terms, $taxonomy, $append = false ) {
 		 * @param string $taxonomy  Taxonomy slug.
 		 */
 		do_action( 'add_term_relationship', $object_id, $tt_id, $taxonomy );
+
 		$wpdb->insert(
 			$wpdb->term_relationships,
 			array(
@@ -2516,6 +2521,7 @@ function wp_set_object_terms( $object_id, $terms, $taxonomy, $append = false ) {
 		 * @param string $taxonomy  Taxonomy slug.
 		 */
 		do_action( 'added_term_relationship', $object_id, $tt_id, $taxonomy );
+
 		$new_tt_ids[] = $tt_id;
 	}
 
@@ -2539,9 +2545,11 @@ function wp_set_object_terms( $object_id, $terms, $taxonomy, $append = false ) {
 	}
 
 	$t = get_taxonomy( $taxonomy );
+
 	if ( ! $append && isset( $t->sort ) && $t->sort ) {
-		$values       = array();
-		$term_order   = 0;
+		$values     = array();
+		$term_order = 0;
+
 		$final_tt_ids = wp_get_object_terms(
 			$object_id,
 			$taxonomy,
@@ -2550,11 +2558,13 @@ function wp_set_object_terms( $object_id, $terms, $taxonomy, $append = false ) {
 				'update_term_meta_cache' => false,
 			)
 		);
+
 		foreach ( $tt_ids as $tt_id ) {
-			if ( in_array( $tt_id, $final_tt_ids ) ) {
+			if ( in_array( (int) $tt_id, $final_tt_ids, true ) ) {
 				$values[] = $wpdb->prepare( '(%d, %d, %d)', $object_id, $tt_id, ++$term_order );
 			}
 		}
+
 		if ( $values ) {
 			if ( false === $wpdb->query( "INSERT INTO $wpdb->term_relationships (object_id, term_taxonomy_id, term_order) VALUES " . join( ',', $values ) . ' ON DUPLICATE KEY UPDATE term_order = VALUES(term_order)' ) ) {
 				return new WP_Error( 'db_insert_error', __( 'Could not insert term relationship into the database.' ), $wpdb->last_error );
@@ -2578,6 +2588,7 @@ function wp_set_object_terms( $object_id, $terms, $taxonomy, $append = false ) {
 	 * @param array  $old_tt_ids Old array of term taxonomy IDs.
 	 */
 	do_action( 'set_object_terms', $object_id, $terms, $tt_ids, $taxonomy, $append, $old_tt_ids );
+
 	return $tt_ids;
 }
 
@@ -3616,8 +3627,10 @@ function _pad_term_counts( &$terms, $taxonomy ) {
 	$tax_obj      = get_taxonomy( $taxonomy );
 	$object_types = esc_sql( $tax_obj->object_type );
 	$results      = $wpdb->get_results( "SELECT object_id, term_taxonomy_id FROM $wpdb->term_relationships INNER JOIN $wpdb->posts ON object_id = ID WHERE term_taxonomy_id IN (" . implode( ',', array_keys( $term_ids ) ) . ") AND post_type IN ('" . implode( "', '", $object_types ) . "') AND post_status = 'publish'" );
+
 	foreach ( $results as $row ) {
-		$id                                   = $term_ids[ $row->term_taxonomy_id ];
+		$id = $term_ids[ $row->term_taxonomy_id ];
+
 		$term_items[ $id ][ $row->object_id ] = isset( $term_items[ $id ][ $row->object_id ] ) ? ++$term_items[ $id ][ $row->object_id ] : 1;
 	}
 
@@ -3627,14 +3640,16 @@ function _pad_term_counts( &$terms, $taxonomy ) {
 		$ancestors = array();
 		while ( ! empty( $terms_by_id[ $child ] ) && $parent = $terms_by_id[ $child ]->parent ) {
 			$ancestors[] = $child;
+
 			if ( ! empty( $term_items[ $term_id ] ) ) {
 				foreach ( $term_items[ $term_id ] as $item_id => $touches ) {
 					$term_items[ $parent ][ $item_id ] = isset( $term_items[ $parent ][ $item_id ] ) ? ++$term_items[ $parent ][ $item_id ] : 1;
 				}
 			}
+
 			$child = $parent;
 
-			if ( in_array( $parent, $ancestors ) ) {
+			if ( in_array( $parent, $ancestors, true ) ) {
 				break;
 			}
 		}
@@ -4522,7 +4537,7 @@ function get_ancestors( $object_id = 0, $object_type = '', $resource_type = '' )
 
 	if ( 'taxonomy' === $resource_type ) {
 		$term = get_term( $object_id, $object_type );
-		while ( ! is_wp_error( $term ) && ! empty( $term->parent ) && ! in_array( $term->parent, $ancestors ) ) {
+		while ( ! is_wp_error( $term ) && ! empty( $term->parent ) && ! in_array( $term->parent, $ancestors, true ) ) {
 			$ancestors[] = (int) $term->parent;
 			$term        = get_term( $term->parent, $object_type );
 		}
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 3c326cfb81..8d62bfae18 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.5-alpha-47556';
+$wp_version = '5.5-alpha-47557';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.