Program: CWE-79
Project: CVE-2020-29171
Buggy source:
<?php

if ( !defined('ABSPATH') ) {
    exit; // Exit if accessed directly
}

if (!class_exists('AIO_WP_Security')){

class AIO_WP_Security{
    var $version = '4.4.5';
    var $db_version = '1.9';
    var $plugin_url;
    var $plugin_path;
    var $configs;
    var $admin_init;
    var $debug_logger;
    var $cron_handler;
    var $user_login_obj;
    var $user_registration_obj;
    var $backup_obj;
    var $scan_obj;
    var $captcha_obj;

    function __construct()
    {
        $this->load_configs();
        $this->define_constants();
        $this->includes();
        $this->loader_operations();

        add_action('init', array(&$this, 'wp_security_plugin_init'), 0);
        add_action('wp_loaded',array(&$this, 'aiowps_wp_loaded_handler'));
        do_action('aiowpsecurity_loaded');
    }

    function plugin_url()
    {
        if ($this->plugin_url) return $this->plugin_url;
        return $this->plugin_url = plugins_url( basename( plugin_dir_path(__FILE__) ), basename( __FILE__ ) );
    }

    function plugin_path()
    {
        if ($this->plugin_path) return $this->plugin_path;
        return $this->plugin_path = untrailingslashit( plugin_dir_path( __FILE__ ) );
    }

    function load_configs()
    {
        include_once('classes/wp-security-config.php');
        $this->configs = AIOWPSecurity_Config::get_instance();
    }

    function define_constants()
    {
        define('AIO_WP_SECURITY_VERSION', $this->version);
        define('AIO_WP_SECURITY_DB_VERSION', $this->db_version);
        define('AIOWPSEC_WP_HOME_URL', home_url());
        define('AIOWPSEC_WP_SITE_URL', site_url());
        define('AIOWPSEC_WP_URL', AIOWPSEC_WP_SITE_URL); // for backwards compatibility
        define('AIO_WP_SECURITY_URL', $this->plugin_url());
        define('AIO_WP_SECURITY_PATH', $this->plugin_path());
        define('AIO_WP_SECURITY_BACKUPS_DIR_NAME', 'aiowps_backups');
        define('AIO_WP_SECURITY_BACKUPS_PATH', AIO_WP_SECURITY_PATH.'/backups');
        define('AIO_WP_SECURITY_LIB_PATH', AIO_WP_SECURITY_PATH.'/lib');
        if (!defined('AIOWPSEC_MANAGEMENT_PERMISSION')){//This will allow the user to define custom capability for this constant in wp-config file
            define('AIOWPSEC_MANAGEMENT_PERMISSION', 'manage_options');
        }
        define('AIOWPSEC_MENU_SLUG_PREFIX', 'aiowpsec');
        define('AIOWPSEC_MAIN_MENU_SLUG', 'aiowpsec');
        define('AIOWPSEC_SETTINGS_MENU_SLUG', 'aiowpsec_settings');
        define('AIOWPSEC_USER_ACCOUNTS_MENU_SLUG', 'aiowpsec_useracc');
        define('AIOWPSEC_USER_LOGIN_MENU_SLUG', 'aiowpsec_userlogin');
        define('AIOWPSEC_USER_REGISTRATION_MENU_SLUG', 'aiowpsec_user_registration');
        define('AIOWPSEC_DB_SEC_MENU_SLUG', 'aiowpsec_database');
        define('AIOWPSEC_FILESYSTEM_MENU_SLUG', 'aiowpsec_filesystem');
        define('AIOWPSEC_BLACKLIST_MENU_SLUG', 'aiowpsec_blacklist');
        define('AIOWPSEC_FIREWALL_MENU_SLUG', 'aiowpsec_firewall');
        define('AIOWPSEC_MAINTENANCE_MENU_SLUG', 'aiowpsec_maintenance');
        define('AIOWPSEC_SPAM_MENU_SLUG', 'aiowpsec_spam');
        define('AIOWPSEC_FILESCAN_MENU_SLUG', 'aiowpsec_filescan');
        define('AIOWPSEC_BRUTE_FORCE_MENU_SLUG', 'aiowpsec_brute_force');
        define('AIOWPSEC_MISC_MENU_SLUG', 'aiowpsec_misc');

        global $wpdb;
        define('AIOWPSEC_TBL_LOGIN_LOCKDOWN', $wpdb->prefix . 'aiowps_login_lockdown');
        define('AIOWPSEC_TBL_FAILED_LOGINS', $wpdb->prefix . 'aiowps_failed_logins');
        define('AIOWPSEC_TBL_USER_LOGIN_ACTIVITY', $wpdb->prefix . 'aiowps_login_activity');
        define('AIOWPSEC_TBL_GLOBAL_META_DATA', $wpdb->prefix . 'aiowps_global_meta');
        define('AIOWPSEC_TBL_EVENTS', $wpdb->prefix . 'aiowps_events');
        define('AIOWPSEC_TBL_PERM_BLOCK', $wpdb->prefix . 'aiowps_permanent_block');

    }

    function includes()
    {
        //Load common files for everywhere
        include_once('classes/wp-security-debug-logger.php');
        include_once('classes/wp-security-utility.php');
        include_once('classes/wp-security-utility-htaccess.php');
        include_once('classes/wp-security-utility-ip-address.php');
        include_once('classes/wp-security-utility-file.php');
        include_once('classes/wp-security-general-init-tasks.php');
        include_once('classes/wp-security-wp-loaded-tasks.php');

        include_once('classes/wp-security-user-login.php');
        include_once('classes/wp-security-user-registration.php');
        include_once('classes/wp-security-captcha.php');
        include_once('classes/wp-security-backup.php');
        include_once('classes/wp-security-file-scan.php');
        include_once('classes/wp-security-cronjob-handler.php');
        include_once('classes/grade-system/wp-security-feature-item.php');
        include_once('classes/grade-system/wp-security-feature-item-manager.php');
        include_once('classes/wp-security-wp-footer-content.php');
        include_once('classes/wp-security-blocking.php');

        if (is_admin()){ //Load admin side only files
            include_once('classes/wp-security-configure-settings.php');
            include_once('admin/wp-security-admin-init.php');
            include_once('admin/general/wp-security-list-table.php');

        }
        else{ //Load front end side only files
        }
    }

    function loader_operations()
    {
        add_action('plugins_loaded',array(&$this, 'plugins_loaded_handler'));//plugins loaded hook

        $debug_config = $this->configs->get_value('aiowps_enable_debug');
        $debug_enabled = empty($debug_config) ? false : true;
        $this->debug_logger = new AIOWPSecurity_Logger($debug_enabled);

        if(is_admin()){
            $this->admin_init = new AIOWPSecurity_Admin_Init();
        }
    }

    static function activate_handler($networkwide)
    {
        global $wpdb;
        //Only runs when the plugin activates
        include_once ('classes/wp-security-installer.php');
        AIOWPSecurity_Installer::run_installer($networkwide);
        AIOWPSecurity_Installer::set_cron_tasks_upon_activation($networkwide);
    }

    static function deactivate_handler($networkwide)
    {
        //Only runs with the pluign is deactivated
        include_once ('classes/wp-security-deactivation-tasks.php');
        AIOWPSecurity_Deactivation::run_deactivation_tasks($networkwide);
        do_action('aiowps_deactivation_complete');
    }

    function db_upgrade_handler()
    {
        if(is_admin()){//Check if DB needs to be upgraded
            if (get_option('aiowpsec_db_version') != AIO_WP_SECURITY_DB_VERSION) {
                include_once ('classes/wp-security-installer.php');
                AIOWPSecurity_Installer::run_installer();
            }
        }
    }

    function plugins_loaded_handler()
    {
        //Runs when plugins_loaded action gets fired
        if(is_admin()){
            //Do plugins_loaded operations for admin side
            $this->db_upgrade_handler();
        }
        $this->do_additional_plugins_loaded_tasks();
    }

    function wp_security_plugin_init()
    {
        //Set up localisation. First loaded overrides strings present in later loaded file
        $locale = apply_filters( 'plugin_locale', get_locale(), 'all-in-one-wp-security-and-firewall' );
        load_textdomain( 'all-in-one-wp-security-and-firewall', WP_LANG_DIR . "/all-in-one-wp-security-and-firewall-$locale.mo" );
	load_plugin_textdomain('all-in-one-wp-security-and-firewall', false, dirname(plugin_basename(__FILE__ )) . '/languages/');

        //Actions, filters, shortcodes goes here
        $this->user_login_obj = new AIOWPSecurity_User_Login();//Do the user login operation tasks
        $this->user_registration_obj = new AIOWPSecurity_User_Registration();//Do the user login operation tasks
        $this->captcha_obj = new AIOWPSecurity_Captcha();//Do the captcha tasks
        $this->backup_obj = new AIOWPSecurity_Backup();//Object to handle backup tasks
        $this->scan_obj = new AIOWPSecurity_Scan();//Object to handle scan tasks
        $this->cron_handler = new AIOWPSecurity_Cronjob_Handler();

        add_action('login_enqueue_scripts',array(&$this, 'aiowps_login_enqueue'));
        add_action('wp_footer',array(&$this, 'aiowps_footer_content'));

        add_action('wp_login', array('AIOWPSecurity_User_Login', 'wp_login_action_handler'), 10, 2);
        do_action('aiowps_force_logout_check');
        new AIOWPSecurity_General_Init_Tasks();
    }

    function aiowps_wp_loaded_handler()
    {
        new AIOWPSecurity_WP_Loaded_Tasks();
    }

    /**
     * Enqueues the Google recaptcha v2 api URL for the standard WP login page
     * @global type $aio_wp_security
     */
    function aiowps_login_enqueue()
    {
        global $aio_wp_security;
        if($aio_wp_security->configs->get_value('aiowps_default_recaptcha')) {
            if($aio_wp_security->configs->get_value('aiowps_enable_login_captcha') == '1' || $aio_wp_security->configs->get_value('aiowps_enable_registration_page_captcha') == '1') {
                wp_enqueue_script( 'google-recaptcha', 'https://www.google.com/recaptcha/api.js', false );
                // below is needed to provide some space for the google reCaptcha form (otherwise it appears partially hidden on RHS)
                wp_add_inline_script( 'google-recaptcha', 'document.addEventListener("DOMContentLoaded", ()=>{document.getElementById("login").style.width = "340px";});' );
            }
        }
    }

    function aiowps_footer_content()
    {
        new AIOWPSecurity_WP_Footer_Content();
    }

    function do_additional_plugins_loaded_tasks()
    {
        global $aio_wp_security;
        if(isset($_GET['aiowpsec_do_log_out']))
        {
            $nonce = isset($_GET['_wpnonce'])?$_GET['_wpnonce']:'';
            if ( !wp_verify_nonce( $nonce, 'aio_logout' ) ) {
                return;
            }
            wp_logout();
            if(isset($_GET['after_logout']))//Redirect to the after logout url directly
            {
                $after_logout_url = esc_url($_GET['after_logout']);
                AIOWPSecurity_Utility::redirect_to_url($after_logout_url);
            }
            $additional_data = strip_tags($_GET['al_additional_data']);
            if(isset($additional_data))
            {
                $login_url = '';
                //Check if rename login feature enabled
                if($aio_wp_security->configs->get_value('aiowps_enable_rename_login_page')=='1'){
                    if (get_option('permalink_structure')){
                        $home_url = trailingslashit(home_url());
                    }else{
                        $home_url = trailingslashit(home_url()) . '?';
                    }
                    $login_url = $home_url.$aio_wp_security->configs->get_value('aiowps_login_page_slug');
                }else{
                    $login_url = wp_login_url();
                }

                //Inspect the payload and do redirect to login page with a msg and redirect url
                $logout_payload = (AIOWPSecurity_Utility::is_multisite_install() ? get_site_transient('aiowps_logout_payload') : get_transient('aiowps_logout_payload'));
                if(!empty($logout_payload['redirect_to'])){
                    $login_url = AIOWPSecurity_Utility::add_query_data_to_url($login_url,'redirect_to',$logout_payload['redirect_to']);
                }
                if(!empty($logout_payload['msg'])){
                    $login_url .= '&'.$logout_payload['msg'];
                }
                if(!empty($login_url)){
                    AIOWPSecurity_Utility::redirect_to_url($login_url);
                }
            }
        }
    }

}//End of class

}//End of class not exists check

$GLOBALS['aio_wp_security'] = new AIO_WP_Security();


Fixed version (ground truth):
<?php

if ( !defined('ABSPATH') ) {
    exit; // Exit if accessed directly
}

if (!class_exists('AIO_WP_Security')){

class AIO_WP_Security{
    var $version = '4.4.6';
    var $db_version = '1.9';
    var $plugin_url;
    var $plugin_path;
    var $configs;
    var $admin_init;
    var $debug_logger;
    var $cron_handler;
    var $user_login_obj;
    var $user_registration_obj;
    var $backup_obj;
    var $scan_obj;
    var $captcha_obj;

    function __construct()
    {
        $this->load_configs();
        $this->define_constants();
        $this->includes();
        $this->loader_operations();

        add_action('init', array(&$this, 'wp_security_plugin_init'), 0);
        add_action('wp_loaded',array(&$this, 'aiowps_wp_loaded_handler'));
        do_action('aiowpsecurity_loaded');
    }

    function plugin_url()
    {
        if ($this->plugin_url) return $this->plugin_url;
        return $this->plugin_url = plugins_url( basename( plugin_dir_path(__FILE__) ), basename( __FILE__ ) );
    }

    function plugin_path()
    {
        if ($this->plugin_path) return $this->plugin_path;
        return $this->plugin_path = untrailingslashit( plugin_dir_path( __FILE__ ) );
    }

    function load_configs()
    {
        include_once('classes/wp-security-config.php');
        $this->configs = AIOWPSecurity_Config::get_instance();
    }

    function define_constants()
    {
        define('AIO_WP_SECURITY_VERSION', $this->version);
        define('AIO_WP_SECURITY_DB_VERSION', $this->db_version);
        define('AIOWPSEC_WP_HOME_URL', home_url());
        define('AIOWPSEC_WP_SITE_URL', site_url());
        define('AIOWPSEC_WP_URL', AIOWPSEC_WP_SITE_URL); // for backwards compatibility
        define('AIO_WP_SECURITY_URL', $this->plugin_url());
        define('AIO_WP_SECURITY_PATH', $this->plugin_path());
        define('AIO_WP_SECURITY_BACKUPS_DIR_NAME', 'aiowps_backups');
        define('AIO_WP_SECURITY_BACKUPS_PATH', AIO_WP_SECURITY_PATH.'/backups');
        define('AIO_WP_SECURITY_LIB_PATH', AIO_WP_SECURITY_PATH.'/lib');
        if (!defined('AIOWPSEC_MANAGEMENT_PERMISSION')){//This will allow the user to define custom capability for this constant in wp-config file
            define('AIOWPSEC_MANAGEMENT_PERMISSION', 'manage_options');
        }
        define('AIOWPSEC_MENU_SLUG_PREFIX', 'aiowpsec');
        define('AIOWPSEC_MAIN_MENU_SLUG', 'aiowpsec');
        define('AIOWPSEC_SETTINGS_MENU_SLUG', 'aiowpsec_settings');
        define('AIOWPSEC_USER_ACCOUNTS_MENU_SLUG', 'aiowpsec_useracc');
        define('AIOWPSEC_USER_LOGIN_MENU_SLUG', 'aiowpsec_userlogin');
        define('AIOWPSEC_USER_REGISTRATION_MENU_SLUG', 'aiowpsec_user_registration');
        define('AIOWPSEC_DB_SEC_MENU_SLUG', 'aiowpsec_database');
        define('AIOWPSEC_FILESYSTEM_MENU_SLUG', 'aiowpsec_filesystem');
        define('AIOWPSEC_BLACKLIST_MENU_SLUG', 'aiowpsec_blacklist');
        define('AIOWPSEC_FIREWALL_MENU_SLUG', 'aiowpsec_firewall');
        define('AIOWPSEC_MAINTENANCE_MENU_SLUG', 'aiowpsec_maintenance');
        define('AIOWPSEC_SPAM_MENU_SLUG', 'aiowpsec_spam');
        define('AIOWPSEC_FILESCAN_MENU_SLUG', 'aiowpsec_filescan');
        define('AIOWPSEC_BRUTE_FORCE_MENU_SLUG', 'aiowpsec_brute_force');
        define('AIOWPSEC_MISC_MENU_SLUG', 'aiowpsec_misc');

        global $wpdb;
        define('AIOWPSEC_TBL_LOGIN_LOCKDOWN', $wpdb->prefix . 'aiowps_login_lockdown');
        define('AIOWPSEC_TBL_FAILED_LOGINS', $wpdb->prefix . 'aiowps_failed_logins');
        define('AIOWPSEC_TBL_USER_LOGIN_ACTIVITY', $wpdb->prefix . 'aiowps_login_activity');
        define('AIOWPSEC_TBL_GLOBAL_META_DATA', $wpdb->prefix . 'aiowps_global_meta');
        define('AIOWPSEC_TBL_EVENTS', $wpdb->prefix . 'aiowps_events');
        define('AIOWPSEC_TBL_PERM_BLOCK', $wpdb->prefix . 'aiowps_permanent_block');

    }

    function includes()
    {
        //Load common files for everywhere
        include_once('classes/wp-security-debug-logger.php');
        include_once('classes/wp-security-utility.php');
        include_once('classes/wp-security-utility-htaccess.php');
        include_once('classes/wp-security-utility-ip-address.php');
        include_once('classes/wp-security-utility-file.php');
        include_once('classes/wp-security-general-init-tasks.php');
        include_once('classes/wp-security-wp-loaded-tasks.php');

        include_once('classes/wp-security-user-login.php');
        include_once('classes/wp-security-user-registration.php');
        include_once('classes/wp-security-captcha.php');
        include_once('classes/wp-security-backup.php');
        include_once('classes/wp-security-file-scan.php');
        include_once('classes/wp-security-cronjob-handler.php');
        include_once('classes/grade-system/wp-security-feature-item.php');
        include_once('classes/grade-system/wp-security-feature-item-manager.php');
        include_once('classes/wp-security-wp-footer-content.php');
        include_once('classes/wp-security-blocking.php');

        if (is_admin()){ //Load admin side only files
            include_once('classes/wp-security-configure-settings.php');
            include_once('admin/wp-security-admin-init.php');
            include_once('admin/general/wp-security-list-table.php');

        }
        else{ //Load front end side only files
        }
    }

    function loader_operations()
    {
        add_action('plugins_loaded',array(&$this, 'plugins_loaded_handler'));//plugins loaded hook

        $debug_config = $this->configs->get_value('aiowps_enable_debug');
        $debug_enabled = empty($debug_config) ? false : true;
        $this->debug_logger = new AIOWPSecurity_Logger($debug_enabled);

        if(is_admin()){
            $this->admin_init = new AIOWPSecurity_Admin_Init();
        }
    }

    static function activate_handler($networkwide)
    {
        global $wpdb;
        //Only runs when the plugin activates
        include_once ('classes/wp-security-installer.php');
        AIOWPSecurity_Installer::run_installer($networkwide);
        AIOWPSecurity_Installer::set_cron_tasks_upon_activation($networkwide);
    }

    static function deactivate_handler($networkwide)
    {
        //Only runs with the pluign is deactivated
        include_once ('classes/wp-security-deactivation-tasks.php');
        AIOWPSecurity_Deactivation::run_deactivation_tasks($networkwide);
        do_action('aiowps_deactivation_complete');
    }

    function db_upgrade_handler()
    {
        if(is_admin()){//Check if DB needs to be upgraded
            if (get_option('aiowpsec_db_version') != AIO_WP_SECURITY_DB_VERSION) {
                include_once ('classes/wp-security-installer.php');
                AIOWPSecurity_Installer::run_installer();
            }
        }
    }

    function plugins_loaded_handler()
    {
        //Runs when plugins_loaded action gets fired
        if(is_admin()){
            //Do plugins_loaded operations for admin side
            $this->db_upgrade_handler();
        }
        $this->do_additional_plugins_loaded_tasks();
    }

    function wp_security_plugin_init()
    {
        //Set up localisation. First loaded overrides strings present in later loaded file
        $locale = apply_filters( 'plugin_locale', get_locale(), 'all-in-one-wp-security-and-firewall' );
        load_textdomain( 'all-in-one-wp-security-and-firewall', WP_LANG_DIR . "/all-in-one-wp-security-and-firewall-$locale.mo" );
	load_plugin_textdomain('all-in-one-wp-security-and-firewall', false, dirname(plugin_basename(__FILE__ )) . '/languages/');

        //Actions, filters, shortcodes goes here
        $this->user_login_obj = new AIOWPSecurity_User_Login();//Do the user login operation tasks
        $this->user_registration_obj = new AIOWPSecurity_User_Registration();//Do the user login operation tasks
        $this->captcha_obj = new AIOWPSecurity_Captcha();//Do the captcha tasks
        $this->backup_obj = new AIOWPSecurity_Backup();//Object to handle backup tasks
        $this->scan_obj = new AIOWPSecurity_Scan();//Object to handle scan tasks
        $this->cron_handler = new AIOWPSecurity_Cronjob_Handler();

        add_action('login_enqueue_scripts',array(&$this, 'aiowps_login_enqueue'));
        add_action('wp_footer',array(&$this, 'aiowps_footer_content'));

        add_action('wp_login', array('AIOWPSecurity_User_Login', 'wp_login_action_handler'), 10, 2);
        do_action('aiowps_force_logout_check');
        new AIOWPSecurity_General_Init_Tasks();
    }

    function aiowps_wp_loaded_handler()
    {
        new AIOWPSecurity_WP_Loaded_Tasks();
    }

    /**
     * Enqueues the Google recaptcha v2 api URL for the standard WP login page
     * @global type $aio_wp_security
     */
    function aiowps_login_enqueue()
    {
        global $aio_wp_security;
        if($aio_wp_security->configs->get_value('aiowps_default_recaptcha')) {
            if($aio_wp_security->configs->get_value('aiowps_enable_login_captcha') == '1' || $aio_wp_security->configs->get_value('aiowps_enable_registration_page_captcha') == '1') {
                wp_enqueue_script( 'google-recaptcha', 'https://www.google.com/recaptcha/api.js', false );
                // below is needed to provide some space for the google reCaptcha form (otherwise it appears partially hidden on RHS)
                wp_add_inline_script( 'google-recaptcha', 'document.addEventListener("DOMContentLoaded", ()=>{document.getElementById("login").style.width = "340px";});' );
            }
        }
    }

    function aiowps_footer_content()
    {
        new AIOWPSecurity_WP_Footer_Content();
    }

    function do_additional_plugins_loaded_tasks()
    {
        global $aio_wp_security;
        if(isset($_GET['aiowpsec_do_log_out']))
        {
            $nonce = isset($_GET['_wpnonce'])?$_GET['_wpnonce']:'';
            if ( !wp_verify_nonce( $nonce, 'aio_logout' ) ) {
                return;
            }
            wp_logout();
            if(isset($_GET['after_logout']))//Redirect to the after logout url directly
            {
                $after_logout_url = esc_url($_GET['after_logout']);
                AIOWPSecurity_Utility::redirect_to_url($after_logout_url);
            }
            $additional_data = strip_tags($_GET['al_additional_data']);
            if(isset($additional_data))
            {
                $login_url = '';
                //Check if rename login feature enabled
                if($aio_wp_security->configs->get_value('aiowps_enable_rename_login_page')=='1'){
                    if (get_option('permalink_structure')){
                        $home_url = trailingslashit(home_url());
                    }else{
                        $home_url = trailingslashit(home_url()) . '?';
                    }
                    $login_url = $home_url.$aio_wp_security->configs->get_value('aiowps_login_page_slug');
                }else{
                    $login_url = wp_login_url();
                }

                //Inspect the payload and do redirect to login page with a msg and redirect url
                $logout_payload = (AIOWPSecurity_Utility::is_multisite_install() ? get_site_transient('aiowps_logout_payload') : get_transient('aiowps_logout_payload'));
                if(!empty($logout_payload['redirect_to'])){
                    $login_url = AIOWPSecurity_Utility::add_query_data_to_url($login_url,'redirect_to',$logout_payload['redirect_to']);
                }
                if(!empty($logout_payload['msg'])){
                    $login_url .= '&'.$logout_payload['msg'];
                }
                if(!empty($login_url)){
                    AIOWPSecurity_Utility::redirect_to_url($login_url);
                }
            }
        }
    }

}//End of class

}//End of class not exists check

$GLOBALS['aio_wp_security'] = new AIO_WP_Security();