The Viral Signup WordPress plugin through 2.1 does not properly sanitise and escape a parameter before using it in a SQL statement via an AJAX action available to unauthenticated users, leading to a SQL injection
The Viral Signup WordPress plugin through 2.1 does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup)