WP Forum Server <= 1.7.3 - Authenticated (Admin+) Stored Cross-Site Scripting

The WP Forum Server plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the (1) groupid parameter in an editgroup action or (2) usergroup_id parameter in an edit_usergroup action in versions up to, and including, 1.7.3 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers with administrative capabilities to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This can also be exploited via CSRF by unauthenticated users due to missing nonce validation.