The Better Messages – Live Chat for WordPress, BuddyPress, PeepSo, Ultimate Member, BuddyBoss plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's 'better_messages_live_chat_button' shortcode in all versions up to, and including, 2.6.9 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.