Keep Backup Daily <= 2.1.2 - Authenticated (Admin+) Stored Cross-Site Scripting via Backup Title

The Keep Backup Daily plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the backup title alias (`val` parameter) in the `update_kbd_bkup_alias` AJAX action in all versions up to, and including, 2.1.2. This is due to insufficient input sanitization and output escaping. While `sanitize_text_field()` strips HTML tags on save, it does not encode double quotes. The backup titles are output in HTML attribute contexts without `esc_attr()`. This makes it possible for authenticated attackers, with Administrator-level access and above, to inject arbitrary web scripts via attribute injection that will execute whenever another administrator views the backup list page.