NewStatPress <= 1.4.5 - Unauthenticated Stored Cross-Site Scripting via 'urlrequested' Attribute via Query String

The NewStatPress plugin for WordPress is vulnerable to Stored Cross-Site Scripting in versions up to, and including, 1.4.5 via the 'Last referrers' meta box on the plugin's Overview admin page. This is due to insufficient output escaping of the visitor-supplied query string that the plugin records in its statistics table: the newstatpress_generate_overview_lastreferrers() function concatenates the stored urlrequested value into a single-quoted href attribute after only FILTER_SANITIZE_URL, which does not encode the apostrophe. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a high-privileged user, such as an administrator, accesses the Overview page and hovers the injected link.