The Simple Banner WordPress plugin before 3.0.4 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 unfilteredhtml capability is disallowed (for example in multisite setup).

The Simple Banner plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the proversionactivationcode parameter in versions up to, and including, 2.11.0 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, including those without administrative capabilities when access is granted to those users, to inject arbitrary web scripts in page that will execute whenever a user role having access to "Simple Banner" accesses the plugin's settings.

The Simple Banner WordPress plugin before 2.12.0 does not properly sanitize its "Simple Banner Text" Settings allowing high privilege users to perform Cross-Site Scripting attacks even when the unfilteredhtml capability is disallowed.

The Simple Banner WordPress plugin before 2.10.4 does not sanitise and escape one of its settings, allowing high privilege users such as admin to use Cross-Site Scripting payload even when the unfilteredhtml capability is disallowed.