Moodle: moodle: authentication bypass via lti provider allows suspended users to gain unauthorized access.

@@ -259,6 +259,20 @@ protected function onLaunch() {
             // Get the updated user record.
             $user = $DB->get_record('user', ['id' => $user->id]);
         } else {
+            if ($dbuser->suspended) {
+                require_once($CFG->libdir . '/authlib.php');
+                $failurereason = AUTH_LOGIN_SUSPENDED;
+                $event = \core\event\user_login_failed::create([
+                    'userid' => $dbuser->id,
+                    'other' => [
+                        'username' => $dbuser->username,
+                        'reason' => $failurereason
+                    ]
+                ]);
+                $event->trigger();
+                throw new \core\exception\moodle_exception('invalidlogin', 'core');
+            }
+
             if (helper::user_match($user, $dbuser)) {
                 $user = $dbuser;
             } else {

@@ -104,6 +104,7 @@ public function user_login($username, $password) {
      * @param int $provisioningmode the desired account provisioning mode, which controls the auth flow for unbound users.
      * @param array $legacyconsumersecrets an array of secrets used by the legacy consumer if a migration claim exists.
      * @throws coding_exception if the specified provisioning mode is invalid.
+     * @throws \core\exception\moodle_exception if user authentication fails.
      */
     public function complete_login(array $launchdata, moodle_url $returnurl, int $provisioningmode,
             array $legacyconsumersecrets = []): void {
@@ -112,6 +113,19 @@ public function complete_login(array $launchdata, moodle_url $returnurl, int $pr
         if ($this->get_user_binding($launchdata['iss'], $launchdata['sub'])) {
             $user = $this->find_or_create_user_from_launch($launchdata);
 
+            if ($user->suspended) {
+                $failurereason = AUTH_LOGIN_SUSPENDED;
+                $event = \core\event\user_login_failed::create([
+                    'userid' => $user->id,
+                    'other' => [
+                        'username' => $user->username,
+                        'reason' => $failurereason
+                    ]
+                ]);
+                $event->trigger();
+                throw new \core\exception\moodle_exception('invalidlogin', 'core');
+            }
+
             if (isloggedin()) {
                 // If a different user is currently logged in, authenticate the linked user instead.
                 global $USER;