PrivateContent Free <= 1.2.0 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'align' Shortcode Attribute

The PrivateContent Free plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'align' shortcode attribute in the [pc-login-form] shortcode in all versions up to, and including, 1.2.0. This is due to insufficient input sanitization and output escaping on the 'align' attribute. Specifically, the attribute value flows from the shortcode through pc_login_form() to pc_static::form_align(), where it is directly concatenated into an HTML class attribute without esc_attr() or any escaping. 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.