Simple Yearly Archive <= 2.2.4 - Authenticated (Contributor+) Stored Cross-Site Scripting

The Simple Yearly Archive plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the `posttype` attribute of the `SimpleYearlyArchive` shortcode in all versions up to, and including, 2.2.4 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.