Fix: Misleading Message When Accessing Admin Menu Page

src/wp-admin/includes/menu.php

@@ -376,7 +376,17 @@ function sort_menu( $a, $b ) {
 }
 unset( $last_menu_key );
 
-if ( ! user_can_access_admin_page() ) {
+if ( ! wp_admin_page_exists() ) {
+
+	/**
+	 * Fires when a request is made to access an admin page that does not exist.
+	 *
+	 * @since 7.2.0
+	 */
+	do_action( 'wp_admin_page_not_found' );
+
+	wp_die( __( 'The requested page does not exist.' ), 404 );
+} elseif ( ! user_can_access_admin_page() ) {
 
 	/**
 	 * Fires when access to an admin page is denied.

src/wp-admin/includes/plugin.php

@@ -1477,12 +1477,13 @@ function add_menu_page( $page_title, $menu_title, $capability, $menu_slug, $call
  * @since 1.5.0
  * @since 5.3.0 Added the `$position` parameter.
  *
- * @global array $submenu
- * @global array $menu
- * @global array $_wp_real_parent_file
- * @global bool  $_wp_submenu_nopriv
- * @global array $_registered_pages
- * @global array $_parent_pages
+ * @global array                              $submenu
+ * @global array                              $menu
+ * @global array                              $_wp_real_parent_file
+ * @global array<string, array<string, true>> $_wp_submenu_nopriv
+ * @global array<string, true>                $_wp_nopriv_pages
+ * @global array<string, true>                $_registered_pages
+ * @global array                              $_parent_pages
  *
  * @param string    $parent_slug The slug name for the parent menu (or the file name of a standard
  *                               WordPress admin page).
@@ -1501,7 +1502,7 @@ function add_menu_page( $page_title, $menu_title, $capability, $menu_slug, $call
  */
 function add_submenu_page( $parent_slug, $page_title, $menu_title, $capability, $menu_slug, $callback = '', $position = null ) {
 	global $submenu, $menu, $_wp_real_parent_file, $_wp_submenu_nopriv,
-		$_registered_pages, $_parent_pages;
+		$_wp_nopriv_pages, $_registered_pages, $_parent_pages;
 
 	$menu_slug   = plugin_basename( $menu_slug );
 	$parent_slug = plugin_basename( $parent_slug );
@@ -1512,6 +1513,7 @@ function add_submenu_page( $parent_slug, $page_title, $menu_title, $capability,
 
 	if ( ! current_user_can( $capability ) ) {
 		$_wp_submenu_nopriv[ $parent_slug ][ $menu_slug ] = true;
+		$_wp_nopriv_pages[ $menu_slug ]                   = true;
 		return false;
 	}
 
@@ -2162,6 +2164,54 @@ function get_plugin_page_hook( $plugin_page, $parent_page ) {
 	}
 }
 
+/**
+ * Determines whether the requested admin page is registered.
+ *
+ * This does not check whether the current user has the capability to access
+ * the page, only whether the page itself exists. Pages registered for a
+ * capability the current user lacks are recorded in the no-privilege
+ * registries rather than in $_registered_pages, and are still considered
+ * to exist so that the caller can report a permission error instead of a
+ * "page not found" error.
+ *
+ * @since 7.2.0
+ *
+ * @global string|null                        $plugin_page        The plugin page slug being loaded.
+ * @global array<string, true>                $_registered_pages  Array of all registered admin page hooks.
+ * @global array<string, true>                $_wp_menu_nopriv    Array of top-level menu slugs the current user cannot access.
+ * @global array<string, array<string, true>> $_wp_submenu_nopriv Array of submenu slugs the current user cannot access, keyed by parent slug.
+ * @global array<string, true>                $_wp_nopriv_pages   Array of page slugs registered for a capability the current user lacks.
+ *
+ * @return bool True if the admin page exists, false otherwise.
+ */
+function wp_admin_page_exists(): bool {
+	global $plugin_page, $_registered_pages, $_wp_menu_nopriv, $_wp_submenu_nopriv,
+		$_wp_nopriv_pages;
+
+	if ( ! isset( $plugin_page ) ) {
+		return true;
+	}
+
+	$hookname = get_plugin_page_hookname( $plugin_page, get_admin_page_parent() );
+
+	if ( isset( $_registered_pages[ $hookname ] ) ) {
+		return true;
+	}
+
+	// The page may be registered for a capability the current user lacks.
+	if ( isset( $_wp_menu_nopriv[ $plugin_page ] ) || isset( $_wp_nopriv_pages[ $plugin_page ] ) ) {
+		return true;
+	}
+
+	foreach ( (array) $_wp_submenu_nopriv as $nopriv_submenus ) {
+		if ( isset( $nopriv_submenus[ $plugin_page ] ) ) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
 /**
  * Gets the hook name for the administrative page of a plugin.
  *
@@ -2202,17 +2252,17 @@ function get_plugin_page_hookname( $plugin_page, $parent_page ) {
  *
  * @since 1.5.0
  *
- * @global string $pagenow            The filename of the current screen.
- * @global array  $menu
- * @global array  $submenu
- * @global array  $_wp_menu_nopriv
- * @global array  $_wp_submenu_nopriv
- * @global string $plugin_page
- * @global array  $_registered_pages
+ * @global string                             $pagenow            The filename of the current screen.
+ * @global array                              $menu               The top-level admin menu items.
+ * @global array                              $submenu            The admin submenu items, keyed by parent slug.
+ * @global array<string, true>                $_wp_menu_nopriv    Array of top-level menu slugs the current user cannot access.
+ * @global array<string, array<string, true>> $_wp_submenu_nopriv Array of submenu slugs the current user cannot access, keyed by parent slug.
+ * @global string|null                        $plugin_page        The plugin page slug being loaded.
+ * @global array<string, true>                $_registered_pages  Array of all registered admin page hooks.
  *
  * @return bool True if the current user can access the admin page, false otherwise.
  */
-function user_can_access_admin_page() {
+function user_can_access_admin_page(): bool {
 	global $pagenow, $menu, $submenu, $_wp_menu_nopriv, $_wp_submenu_nopriv,
 		$plugin_page, $_registered_pages;
 

tests/phpstan/baselines/offsetAccess.nonOffsetAccessible.neon

@@ -23,11 +23,6 @@ parameters:
 			identifier: offsetAccess.nonOffsetAccessible
 			count: 4
 			path: ../../../src/wp-admin/includes/class-wp-debug-data.php
-		-
-			message: '#^Cannot access offset mixed on bool\.$#'
-			identifier: offsetAccess.nonOffsetAccessible
-			count: 1
-			path: ../../../src/wp-admin/includes/plugin.php
 		-
 			message: '#^Cannot access offset ''new_version'' on bool\.$#'
 			identifier: offsetAccess.nonOffsetAccessible

tests/phpunit/tests/admin/includesPlugin.php

@@ -26,13 +26,19 @@ public function tear_down() {
 	 * Resets the global menu registries modified by the menu API tests.
 	 */
 	private function reset_menu_globals() {
-		global $menu, $submenu, $admin_page_hooks, $_registered_pages, $_parent_pages;
+		global $menu, $submenu, $admin_page_hooks, $_registered_pages, $_parent_pages,
+			$_wp_menu_nopriv, $_wp_submenu_nopriv, $_wp_nopriv_pages;
 
-		$menu              = array();
-		$submenu           = array();
-		$admin_page_hooks  = array();
-		$_registered_pages = array();
-		$_parent_pages     = array();
+		$menu               = array();
+		$submenu            = array();
+		$admin_page_hooks   = array();
+		$_registered_pages  = array();
+		$_parent_pages      = array();
+		$_wp_menu_nopriv    = array();
+		$_wp_submenu_nopriv = array();
+		$_wp_nopriv_pages   = array();
+
+		unset( $GLOBALS['plugin_page'] );
 	}
 
 	public static function wpSetUpBeforeClass( $factory ) {
@@ -97,6 +103,103 @@ public function test_menu_page_url() {
 		wp_set_current_user( $current_user );
 	}
 
+	/**
+	 * @ticket 14060
+	 *
+	 * @covers ::wp_admin_page_exists
+	 */
+	public function test_wp_admin_page_exists_returns_true_when_no_plugin_page_is_set() {
+		unset( $GLOBALS['plugin_page'] );
+
+		$this->assertTrue( wp_admin_page_exists() );
+	}
+
+	/**
+	 * @ticket 14060
+	 *
+	 * @covers ::wp_admin_page_exists
+	 */
+	public function test_wp_admin_page_exists_returns_true_for_a_registered_page() {
+		global $pagenow, $plugin_page;
+
+		wp_set_current_user( self::$admin_id );
+
+		add_options_page( 'Test Settings', 'Test Settings', 'manage_options', 'testsettings', 'mt_settings_page' );
+
+		$original_pagenow = $pagenow;
+		$pagenow          = 'options-general.php';
+		$plugin_page      = 'testsettings';
+
+		$exists = wp_admin_page_exists();
+
+		$pagenow = $original_pagenow;
+
+		$this->assertTrue( $exists );
+	}
+
+	/**
+	 * @ticket 14060
+	 *
+	 * @covers ::wp_admin_page_exists
+	 */
+	public function test_wp_admin_page_exists_returns_false_for_an_unregistered_page() {
+		global $plugin_page, $_registered_pages;
+
+		$plugin_page       = 'does-not-exist';
+		$_registered_pages = array();
+
+		$this->assertFalse( wp_admin_page_exists() );
+	}
+
+	/**
+	 * Pages the current user cannot access are not added to $_registered_pages,
+	 * but they do exist and must not be reported as missing.
+	 *
+	 * @ticket 14060
+	 *
+	 * @covers ::wp_admin_page_exists
+	 */
+	public function test_wp_admin_page_exists_returns_true_for_a_registered_page_the_user_cannot_access() {
+		global $plugin_page;
+
+		wp_set_current_user( self::$admin_id );
+
+		add_menu_page( 'Test Toplevel', 'Test Toplevel', 'manage_options', 'mt-top-level-handle', 'mt_toplevel_page' );
+
+		// Register a submenu page requiring a capability no user has.
+		wp_set_current_user( 0 );
+		add_submenu_page( 'mt-top-level-handle', 'No Priv', 'No Priv', 'do_not_allow', 'mt-no-priv', 'mt_no_priv_page' );
+
+		$plugin_page = 'mt-no-priv';
+
+		$this->assertTrue( wp_admin_page_exists() );
+	}
+
+	/**
+	 * The no-privilege menu registries are reset in menu.php after the
+	 * `_admin_menu` hook fires, so pages registered before that must still
+	 * be considered to exist.
+	 *
+	 * @ticket 14060
+	 *
+	 * @covers ::wp_admin_page_exists
+	 */
+	public function test_wp_admin_page_exists_returns_true_for_an_inaccessible_page_after_nopriv_registries_are_reset() {
+		global $plugin_page, $_wp_menu_nopriv, $_wp_submenu_nopriv;
+
+		wp_set_current_user( 0 );
+
+		add_submenu_page( 'options-general.php', 'No Priv', 'No Priv', 'do_not_allow', 'mt-no-priv', 'mt_no_priv_page' );
+
+		// Simulate menu.php resetting the registries.
+		$_wp_menu_nopriv    = array();
+		$_wp_submenu_nopriv = array();
+
+		$plugin_page = 'mt-no-priv';
+
+		$this->assertTrue( wp_admin_page_exists() );
+	}
+
 	/**
 	 * Tests the position parameter.
 	 *